Level 1
I think you’re better off taking your first level in Fighter, or an alternative, than Artificer. It’s a difference between more HP and more skills, but I don’t think you’re going to use a lot of skills beyond Craft and Use Magic Device. But I’d probably rather something better than Fighter...
Problems with Fighter
I don’t think Fighter offers very much here. The class is generally quite poor, and only a good idea if there are a series of specific feats you have in mind that you cannot get any other way.
Note that tanking in 3.5 is not easy; the system does not offer very many ways to do it effectively. You cannot simply be capable of taking a lot of damage, you also have to be able to handle a wide variety of magical effects so you cannot get sidelined, and you need to be a real threat in your own right so you don’t get ignored.
Fighter can offer these things with very careful feat selection, but there are better ways. You don’t need proficiency in any particular armor, you’re not using Tower Shields, and Base Attack Bonus and large HD are available on other, better classes. The Fighter’s notoriously weak Will save (that 12 is quite likely to go into Wisdom) mean that spellcasters may be able to very trivially prevent you from protecting anyone.
If you insist on Fighter, though, you can do a lot to salvage the class by using the Dungeoncrasher alternate class feature in Dungeonscape. Get Improved Bull Rush, Shock Trooper (Complete Warrior), and go to town on enemies. If you go this route, you’ll want exactly 6 levels of Fighter. At which point, you’ll qualify for Warforged Juggernaut, which I strongly recommend here.
Alternative Martial Base Classes
Just from Core classes, Barbarian is a very good choice. You cannot use Infusions while Raging, but most melee Artificers are about long-term buffs, which don’t go away when you Rage. If you have Complete Champion, you can get Pounce instead of Fast Movement: getting the ability to move and full-attack is paramount to your ability to actually be threat enough to draw enemies’ fire away from your allies.
Of course, as is usually the case in these discussions, Crusader and Warblade from Tome of Battle are far superior choices. The Crusader, in particular, gets some of the very-few true aggro-controlling abilities in the game.
For completeness, I’ll also point out the Knight from Player’s Handbook II. It’s unfortunately rather underwhelming, but Test of Mettle is one of the other very few aggro-controlling abilities in 3.5. It’s got a lot of limitations, lots of things are immune to it, and the DC depends on Knight levels (of which, most are bad) and Charisma (which Warforged take a penalty to), so I don’t really recommend Knight.
Recommended Prestige Classes
The Warforged Juggernaut from Eberron Campaign Setting is an excellent choice for prestige class, regardless of how you start. The immunities it gives you are great for not getting sidelined too easily. It’s prerequisites are also ideal for a Dungeoncrasher; a Dungeoncrasher Fighter 6/Warforged Juggernaut 10 is a pretty solid, simple build. I wouldn’t bother with Artificer as a Dungeoncrasher, though; you won’t be able to fit in enough levels to make it worth it.
If you do go with a Barbarian/Artificer, you may find Rage interfering with your infusions/magic items. There is no official way around this, but you might ask your DM if you could adapt Rage Mage (Complete Warrior) to allow you to enter with 2nd-level Infusions instead of 2nd-level Spells, and have Spell Rage apply to infusions and magic items instead of spells. It’s a pretty minor change, and Rage Mage is hardly an amazing class, so it might fly. Personally, though, I think it’s unnecessary; simply being careful about when you start to Rage should be enough. Combat Casting is a pretty obnoxious feat tax.
Something Different: Straight Artificer
I’d also seriously consider straight Artificer, since the Warforged substitution levels in Races of Eberron are quite good. Your base HP will be low (but you should have high Constitution), and ¾ BAB will hurt (but probably not as much as you think), but personally I’d want to get Artificer 5 sooner rather than later. Artificers also get pretty solid tanking abilities, since they can get things like wand of shield other, and various survival spells and infusions. Magic items can go a very long way to shoring up the Artificer’s weaknesses (actually, at high levels of optimization, the Artificer is one of the strongest classes in the game, and capable of utterly devastating any of the other classes I’ve mentioned in this answer; that’s non-trivial to accomplish though).
Personal Suggestion
I'd probably dip Barbarian, take Artificer long enough to get some useful abilities, and then go with Warforged Juggernaut. You don’t quite qualify for Juggernaut as a Barbarian 1/Artificer 5, so a dip into Crusader for some maneuvers would be a good idea. Alternatively, I might drop that level into Rage Mage if I could convince my DM to allow the adaptation, but only if I really felt the like Rage was interfering too much; I don’t think it would really.
So I’d plan on something like Barbarian 1/Artificer 5/Crusader 1/Warforged Juggernaut 10 or Barbarian 1/Artificer 5/Rage Mage 1/Warforged Juggernaut 10.
If Fighter needs to be a part, I’d go Fighter 6 with Dungeoncrasher, and never look back: I’d enter Warforged Juggernaut at that point, and if I finished it, I’d find something else to do. Without Dungeoncrasher, I think Fighter levels are largely a waste of time.
Caveat the First: I Am Making Broad Generalizations
There are cases where you might want to break these.
Caveat the Second: I Am Not Overly Familiar With Pathfinder
I have read the Core rule book, but none of the supplemental material, including the archetypes (alternate class features in 3.5 lingo), and Paizo did make it a goal to counter, at the very least, my point #2. Within the Core material that I have read, I would argue that they largely failed. I have heard that they have done somewhat better with the supplemental material, but I would not know. Mostly, the answer is really only being given for 3.5, with the understanding that Pathfinder Core changed very little in any significant way.
Caveat the Third: I View Classes as Purely Metagame Concepts
I have little to no problem with multiclassing, even a great deal of multiclassing, because in my games a character does not think of himself as a Paladin 6 or a Barbarian 2/Rogue 1/Cleric 1/Swordsage 2 – he thinks of himself as a knight, or a mercenary, or a mystic, or whatever.
Or, say, a Monk 2/Paladin 6 thinks of herself as a Samurai.
Each class is, as far as I am concerned, a bundle of mechanical features with some suggested ideas for what sort of person would have them. Players at my table know, for instance, that they don’t even have to ask if they want to treat, for instance, Rage as instead “Zen Focus,” so long as the mechanics do not change. Most abilities are reasonably generic and can be understood as a lot of possible things in character.
Multiclass characters can represent a change of heart – someone who used to train one way abandoning it for another – but particularly when you start at levels above 1 and you start with levels in a few classes, it often makes more sense to think of a multiclassed character as someone who pursued one path their whole life – that path is just mechanically represented by different classes.
1. Spellcasters should not multiclass
Spellcasters, as well as manifesters, will always benefit most from getting the highest-level spells (powers) available at a given level. Their spellcasting (manifesting) progressions benefit only from more (effective) levels in their class.
Note that technically in 3.5 jargon, prestige classes do not count as multiclassing, but a separate thing. Prestige classes can be very good for spellcasters, since they frequently have few or no class features aside from their spellcasting, and many prestige classes advance spellcasting on a 1:1 basis. In some cases, this can literally be “something for nothing,” as the prestige class provides class features while not costing a spellcaster anything from their base class.
2. Mundanes should multiclass
Mundane classes (and the weaker half-casters, usually the ones who stop at 4th-level spells) do not have a solid progression like spellcasters do. Furthermore, most of them are extremely front-loaded. For examples:
- Barbarian gives Rage, and potentially Pounce (Lion Spirit Totem, Complete Champion) in one level. Level 2 can get you Improved Trip without prerequisites (Wolf Totem, Unearthed Arcana). Beyond that, the next significant benefit comes at 11th level (Greater Rage).
- Fighter gives a lot of proficiencies and a feat at 1st level, and another feat at 2nd, but nothing at third, and thereafter the rate of ½ feats per level, which is not good.
- Monk gives a couple of feats in addition to improved Improved Unarmed Strike, plus Evasion and Flurry of Blows, in the first two levels. It proceeds to give nothing much for the next 18.
- Ninja (Complete Adventurer) gets Ghost Step at 2nd, and little else until it gains the ability to become Ethereal.
- Ranger can get some combat feats without prerequisites and gets a feat per level until 3rd, but is overall not a great class.
- Rogue, and most Sneak Attack-ing classes, grant 1d6 Sneak Attack damage each odd level. By taking an odd number of levels in multiple Sneak Attack-granting classes, you can gain higher Sneak Attack damage than a single-classed Rogue would get.
And so on. So a Barbarian 2/Fighter 2/Monk 2/Paladin 2 has way more class features than a Barbarian 8, Ranger 8, Fighter 8, or Paladin 8.
Note that Cleric 1 is quite probably the best single-level dip in the game, despite also being a fullcaster that you can focus all 20 levels on. In this sense, Clerics are both martial and magical. Even characters without enough Wisdom to cast Cleric spells can make good use of a Cleric dip.
Psychic Warriors are another exception: if you aren’t absolutely requiring full BAB, Psychic Warrior 2 can get you the same feats that Fighter 2 can, plus a few Powers which can be very useful to an otherwise-mundane warrior.
3. Those in between can go either way or, sometimes, halfway between
You can dip Bard for Bardic Knowledge, Inspire Courage, and fascinate, or you could focus on Bard to get its quality spellcasting. Binders (Tome of Magic) and meldshapers (Magic of Incarnum) can be dipped for a select Vestige or Chakra bind, or focused on to maximize those features.
Factota (Dungeonscape) go even further and are solid at 1 (all skills in class), 3 (Brains over Brawn), 8 (Cunning Surge), or 20 levels. Binders and meldshapers are also reasonably good at being worth however many levels of them you want to take.
4. Tome of Battle is exceptional and unique
Tome of Battle classes multiclass better than any other classes in the system, because they add half their level in other classes to their Initiator Level, and can select higher-level maneuvers based on this improved Initiator Level. That means unlike a Fighter 8/Wizard 1, who gets 1st-level spells, a Fighter 8/Warblade 1 has Initiator Level 5 and gets 3rd-level maneuvers.
Ardents (Complete Psionic) have a somewhat-similar mechanic for determining what level of power they can use, but no built-in bonuses to their Manifester Level from other classes. The Practiced Manifester feat (also Complete Psionic), however, means that an Ardent can take up to 4 levels in other classes while maintaining full Manifester Level and therefore the highest-level powers.
Best Answer
Spells and Swords
The typical “goal” of a gish is 9th-level powers or spells (usually a minimum of 17 effective levels in the manifesting or spellcasting class) and BAB +16 (full four attacks from BAB, usually a minimum of 11 full-BAB levels).
Race
Generally speaking, your priorities are:
No LA or RHD. Either means lost spellcasting for that level.
No penalty to your spellcasting ability score.
No penalty to Constitution.
No penalty to Strength (unless ranged or finesse, in which case replace this with Dexterity).
Relevant bonus feats.
Bonus to your spellcasting ability score.
Bonus to relevant caster levels.
Bonus to Constitution.
Bonus to Strength (unless ranged or finesse, then Dexterity).
Human
Well, duh. No penalties, and gives a bonus feat of your choice. That hits priorities 1-5, and almost nothing else is going to hit #5.
Consider the Azurin (Magic of Incarnum), which is a human that trades the bonus skill point for a point of Essentia. Essentia is fairly useful if you can spare feats for Shape Soulmeld and/or Open Chakra. Also, the Silverbrow Human (Dragon Magic) is a good choice if the (Dragonblood) subtype is necessary for anything you like (especially important for bards; see below).
Dwarf
Mediocre choice on its own (bonuses to Constitution and saving throws are nice, but not nearly as good as a bonus feat), but allows entry into the excellent Runesmith prestige class.
Gray Elf / Fire Elf
The gray elf or fire elf get bonuses to Intelligence from Core/SRD material, and the Races of the Wild elven generalist wizard variant is rather solid. And the elven racial weapon proficiencies are nice for entering Abjurant Champion (it requires a martial weapon proficiency), though at best they’re worth a single feat. And of course, the penalty to Constitution is a big no-no, so I don’t truly recommend it.
Strongheart Halfling
If you’re unfamiliar, these are basically Small-size humans, stat-wise.
Small size is a pretty big boon: improved attack, AC, stealth-skill modifiers.
On the other hand, it hurts your damage somewhat, and makes it somewhat harder to get reach (a single size increase won’t get you any).
Usually spellcasters greatly prefer this (to the point it’s considered a fairly cheesy option), but for you I don’t think it’s ideal.
Gnome
Bonuses to illusion spells (and illusion spells are very good for a gish), and bonus to Constitution. Solid choice, though between Small size and Strength penalty, it’s a far better choice for a ranged character than a melee one.
The forest gnome is strictly superior to the default rock gnome, by the way. Also consider the whisper gnome (Races of Destiny): a fantastic stealth race, it could be excellent if your swordsmanship is a little sneakier.
Lesser Aasimarr
Overpowered, but these are the only race that combines three nice features: LA +0, +2 Charisma, and no penalty to Constitution. In fact, they have no ability score penalties at all and they also give +2 Wisdom, because like I said, they’re overpowered. If they’re allowed, they’re kind of an obvious choice for Charisma- or Wisdom- based gishes.
Black Ethergaunt
If you are starting at ECL 20th, these monstrosities are... absurd. Perhaps not as good with a weapon as you might like (“only” BAB +12), they’re still ridiculously good, with ludicrous ability score bonuses, powerful special attacks, spell immunity, and they cast as 17th-level wizards.
In reality, don’t do this. You’re better than that.
Base Classes
Usually this will be your source of spellcasting. Martial base classes do have the nice property of being heavily front-loaded (i.e. you can get a lot in a few levels), but by definition you will not be getting spellcasting for doing so. I’ll note a couple of exceptions, however.
Wizard
Pretty much the be-all, end-all of arcane spellcasting classes. Wizards have the best spell list in the game, an inherently forgiving spellcasting mechanic (preparation allows you to change your loadout every day), and specialization allows you to get more spell slots. They also get a couple of bonus feats, which are very useful for qualifying for prestige classes.
See my other answer for suggestions about specializing; being a gish doesn’t change things much. If anything, the general suggestion of banning Enchantment and Evocation becomes that much stronger, since few Enchantments help you in melee much, and you are supposedly handling direct-damage with your sword.
Sha’ir
This very-weird class from Dragon Compendium has 0th-9th level spells, some arcane and some divine, weirdly enough. A neat trick there is that you can use Alternate Source Spell (Dragon vol. 325) to cast your arcane spells as divine spells that ignore Arcane Spell Failure. Anyway, the other reason to consider sha’ir is that it’s a charisma-based prepared-spellcasting class, which among other things means it gets each spell level after 1st a level earlier than other charisma-based spellcasters. This is very relevant if you want to use charisma-focused options like Divine Grace.
Sorcerer
The more static, Charisma-based wizard. Doesn’t really offer much that the wizard doesn’t do better, though there’s something to be said for having more spell slots for Arcane Strike purposes (but then the difference between a sorcerer and a specialist wizard in that regard are somewhat minimal), and as will become something of a theme, being Charisma-based is very, very nice for certain builds.
Avoid the battle sorcerer and stalwart sorcerer; they permanently inhibit your spellcasting for the purposes of improving your sorcerer class levels; since you’ll be aiming to take as few of those as possible, there’s just not much point. The only way it works out is if they allow you to take fewer sorcerer class levels and get into a prestige class sooner, but that’s uncommon and usually still not worth it. Battle sorcerer 20 is arguably superior to sorcerer 10/eldritch knight 10, though, so in an SRD-only game it may be the only game in town.
Wu Jen
Complete Arcane’s wu jen are very similar to wizards (spellbook-prepared, intelligence-based spellcasting from 0th-9th level), with a different spell list. Ultimately, that spell list is much weaker, though still plenty powerful, and wu jen do have a few unique spells that are worthwhile for a gish (such as giant’s size for the rare multiple-category size increase, and the various ribbon spells which require a real attack, rather than a touch attack, to land).
Psion
Intelligence-based psionic manifester, though he plays more like a sorcerer in terms of mechanics. A number of powers are quite useful here, though you may need Expanded Knowledge for some of the best of them. The psicrystal is also very useful: manifesting share pain on it and then sharing a vigor power between you effectively doubles the amount of temporary hit points that vigor gives you, and having your psicrystal handle concentrating on control body effectively allows you to use your intelligence score for your attack stats, which is very nice (and otherwise very difficult).
Erudite
Complete Psionics offers a psion variant called the erudite, with much more wizard-like mechanics. The rules are somewhat ambiguous about whether the number listed for Unique Powers per Day are for each level, or total, which makes a huge difference in how good the class is (if the former, it’s massively superior to the psion; if the latter, it’s probably a bit worse).
Mind’s Eye: Expanded Classes Part Four details, among other things, the “Spell to Power” erudite, which is phenomenally powerful (because you get access to, well, all spells ever); most DMs will ban it. It does basically eliminate the need for refluffing your psionics as spellcasting, since they are actually using spells, but it’s also ridiculously broken. In fact, if UPD is treated as per-power-level, then StP Erudite is the single most powerful class in the game.
Psychic Warrior
Probably the best “gish-in-a-can” class, psychic warriors are extremely competent. Their ability to manifest natural weapons allows them to do devastating melee damage, they have numerous defensive powers like vigor, and powerful mobility options like hustle and psionic lion’s charge are available to them. Plus expansion is the single-best size-increasing ability in the game. And they come with ¾ BAB per level, which is quite solid.
Ardent
The one good class in Complete Psionics (seriously), ardents are ¾ BAB per level, and get 9th-level powers unlike psychic warriors. Unfortunately, while they get great mobility powers like the psychic warrior, they miss out on some key stuff like expansion and vigor. Recommended only if the mantle substitution rules are allowed.
Wilder
Wilders just... don’t offer very much here. They get fewer powers than the psion, don’t get access to any specialty powers, and Wild Surge is frequently far too risky to use (and the Overchannel feat accomplishes the same thing, but better).
Bard
The bard is a very capable warrior if built right, primarily by using Snowflake Wardance (Frostburn), Song of the White Raven (Tome of Battle), and harmonizing crystal echoblades (harmonizing and crystal echoblades are both found in Magic Item Compendium). See my previous answer about bards for more on how to make the most of them.
Note that a 2-level dip in paladin works extremely well for bards because of Divine Grace, but also that the Harmonious Knight variant (Champions of Valor) can actually replace bard in certain cases. Also note the Sublime Chord (Complete Arcane) prestige class for getting your spellcasting back up to snuff.
Duskblade
A solid “gish-in-a-can”, the duskblade from Player’s Handbook II gets a very useful ability to channel touch spells through an attack. Unfortunately, their spell list is really limited (and goes only to 6th-level spells), and the really good feature (full-attack spell channeling) doesn’t come until 13th class level, which is very rough. Still, for arcane spellcasting, full BAB, and simplicity, duskblade wins by a landslide; every other option requires extensive use of prestige classes to accomplish it. They just wind up better when they do that.
You can also try three levels here for grabbing Arcane Channeling and some BAB, and then go into some other spellcasting class. Arcane Channeling works with any spell (they don’t even have to be arcane!), but ultimately the addition of weapon damage isn’t worth the lost spellcasting levels. There’s no reasonable way to get the 13th-level full-attack version and some other form of spellcasting, sadly.
Paladin
The one notable exception to focusing on spellcasting in your base classes, paladins get the very nice Divine Grace at 2nd level, which is phenomenal on Charisma-based spellcasters. The bumps to BAB and HP are also nice. Combined with sorcerer, this forms the basis of “sorcadin” builds. There is absolutely no reason to go for more than 2 levels of paladin in a gish build, however.
The Harmonious Knight paladin variant in Champions of Valor is an excellent option, by the way, giving you a single use of Inspire Courage, as the bard class feature. Can work very nicely as a replacement for bard in Charisma-to-everything builds.
Hexblade
The hexblade from Complete Warrior is, sadly, pretty weak. The author even admitted as much in hindsight; that early in 3.5’s development (Complete Warrior was the first supplement published) they over- and under-estimated quite a lot of things. As a result, the hexblade gets too little spellcasting too late; the only really nice thing they get is Arcane Resistance (Cha to saves vs. spells) and the Player’s Handbook II ACF that swaps the 4th-level Familiar for the excellent Dark Companion. Viable for a two-level dip to do a non-LG sorcadin, but otherwise pretty meh. Bear in mind that Divine Grace is vastly superior to Arcane Resistance, since Divine Grace is not only vs. spells.
Spellcasting-progression Prestige Classes
This is where you get your BAB back, from full-BAB or medium-BAB spellcasting prestige classes. I’m not going to list every option (for instance, you can technically take a single level of each of Thrall to Demogorgon and Thrall to Orcus, but that’s unlikely to go well for you), just the notable ones.
Abjurant Champion
This is the go-to; you will want all five levels in this Complete Mage class. Its full-BAB, full-spellcasting is unique, and it’s class features are all pretty solid, too.
Entry requires proficiency in a martial weapon; this is a point where elves suddenly become more desirable than usual, because they start with four. For others, though, you just need to burn a feat (and if you’re a wizard you can get them as one of your bonus feats), you can dip some martial class and lose spellcasting, or you can dip Dragonslayer, below.
Not really much else to say here, it’s just really, really good.
Jade Phoenix Mage
This prestige class from Tome of Battle combines arcane spellcasting with martial maneuvers, and is therefore excellent. It has a number of potent class features as well, though it does lose a fair amount of spellcasting in the process. It’s actually worth considering the loss of yet another level to dip crusader (also Tome of Battle) before entry, as that will cover the prerequisites more easily, you’ll have some Devoted Spirit maneuvers for the purposes of having the prereqs for the maneuvers that Jade Phoenix Mage grants, and the crusader’s recovery mechanic is excellent.
The optimal entry is spellcaster 8/crusader 1; this allows you to have Initiator Level 5 at crusader 1, netting you up to five 3rd-level maneuvers and a 3rd-level stance in one level.
Swiftblade
From this web article, the swiftblade is possibly unique in 3.5 as having been massively overhauled following player input. While it was originally a thoroughly typical and mediocre gish prestige class, it is now an excellent and unique class, trading a lot of spellcasting and actually making up for it with really potent time-based abilities. Very specialized, but strongly worth considering.
Dragonslayer
This class from Draconomicon is thoroughly mediocre, but it does give you three very useful things at 1st level: +1 BAB, +1 level of existing spellcasting class, and (most importantly), proficiency with all martial weapons. This is the only way to get that proficiency as a spellcaster without losing spellcasting. It is therefore very good, because you need that proficiency for a lot of gish prestige classes. Not worth taking more than one level of.
Runesmith
Runesmith is a dwarf-only prestige class from Races of Stone that has full spellcasting, but only the typical spellcaster ½ BAB per level. That said, at first level, it grants you the ability to waive the Somatic components from every spell you ever cast. If that doesn’t seem particularly important to you, note that Arcane Spell Failure only applies to spells with Somatic components. Runesmith is the best way to wear heavy armor while spellcasting. The remaining levels are pretty solid, too, but the poor BAB won’t help your swording.
If you are not a dwarf or otherwise do not want to use runesmith, but still want to wear real armor, see my other question about handling arcane spell failure. Note that since you want the BAB, Abjurant Champion is already a close to must-have for you, and that class obviates a lot of the advantages that armor provides.
Eldritch Knight
The Core option. You basically would rather not wind up here if you can; the class feature is fairly meh, the requirements are obnoxious (but see Dragonslayer above for a way to meet them without losing spellcasting), and you’re guaranteed to lose a spellcasting level. Unfortunately, if you want BAB +16, you are very likely to wind up here or in Knight Phantom, below, because they’re simply the largest chunks of full-BAB spellcasting in the game.
Knight Phantom
This prestige class from Five Nations has very similar requirements to the Eldritch Knight, and the same BAB/saves/spellcasting progressions, but has much, much better class features. Like the Eldritch Knight, it’s unavoidable to lose one spellcasting level before entry, but that level is very difficult to avoid in any event. Again, taking a level of Dragonslayer is preferred to a level of some martial base class if you can swing the feats.
Unseen Seer
This class is more of a skillmonkey-mage than it is a warrior-mage, but it does get ¾ BAB per level, full spellcasting, and a bunch of really nice features on top of its 6+Int skill points. Very solid in general, also ideal for getting those last few levels of decent BAB necessary to hit BAB +16 without losing a spellcasting level.
If you want to use the unseen seer’s improvement to precision damage, but don’t want to dip rogue or whatever, you can use Martial Study (assassin’s stance) at 10th-or-higher to get +2d6 Sneak Attack damage, and thus give unseen seer something to improve. This will require Martial Study in some Shadow Hand maneuver, but that also gets you Hide as always-a-class-skill, which will help.
Ultimate Magus
I mention this only because you did; I would not otherwise consider it a gish prestige class. It’s certainly a cool prestige class, but advancing duskblade spellcasting isn’t worth it simply because duskblade spellcasting isn’t all that good; it’s the Arcane Channeling that you want. If you do want to go this route, the typical pairing with wizard is beguiler (Player’s Handbook II), though the Core assassin makes an interesting entry (albeit not a particularly good one).
Prestige Classes with their own spellcasting
There are a lot of these, and several even have good BAB, but most have really poor spell lists. I’m only going to bother with two.
Suel Arcanamach
This class from Complete Arcane is pretty cool, though honestly you are way, way better off just going straight battle sorcerer (and remember, I consider battle sorcerer quite poor). Still, it’s simple, it has nice class features, and it does well out of the box.
Might be interesting on a paladin 2/duskblade 3 entry. You might even be able to finagle entry into sublime chord (see below) after that, to put your spellcasting in a better place.
Sublime Chord
This prestige class from Complete Arcane gets you 9th-level charisma-based spells off the Sor/Wiz in as many levels. As such, it is an amazing way to “catch up” if you are behind.
This one is generally for bards, though an entry that uses Harmonious Knight paladin 2 and sorcerer 6 -or- sha’ir 5 might be better, since it gets you Divine Grace.
A nice trick with sublime chord is to take classes that miss spellcasting in early levels, say Knight Phantom, before you enter sublime chord, getting the dead levels over with before they really matter. You then use the remaining levels to continue to advance Sublime Chord spellcasting, allowing you to get that full BAB on excellent spellcasting, and the lost spellcasting level of the first prestige class doesn’t come into play because it was from before you started Sublime Chord.
Manifesting Prestige Classes
Easy section because there are only two that give full BAB.
Slayer
The SRD version (rather than the one in Expanded Psionics Handbook) is much better since its features are not restricted to just illithids. Either way, though, lose a manifesting level, gain full BAB and a ton of really nice class features. Excellent class.
War Mind
This one is full BAB, and gets its own manifesting, Wis-based off the psychic warrior list. Overall, psychic warrior into slayer is better, though Sweeping Strike plus Cleave is a terrifying combo, particularly if you have a cheap and efficient way to add a lot of weak enemies to the map around you (a bag of rats is traditional).
Recommended Builds
I am listing these in order of simplest and most generic, to the highly specialized. Note that the specialized builds are more powerful; if they weren’t they wouldn’t be worth worrying about the trouble of the whole build.
Gish-in-a-can
Simply being a duskblade (to 13th, at least), bard (potentially with full-BAB prestige classes), or a psychic warrior (to 20th, or with 10 levels of Slayer) makes you a reasonably solid gish. By far the simplest answer. Of these, the psychic warrior/slayer is best, then the bard, then the duskblade.
Sorcadin
These are basically the standard Paladin 2/Sorcerer chassis, taken in various directions. Divine Grace is quite nice, it gets you some BAB, makes entry into Eldritch Knight and/or Knight Phantom easier.
Of these, only the first and last ones get 9th-level spells, but the BAB +12 of the first one isn’t that impressive. The last gets BAB +16, which is the magic number, and is probably the simplest build to do the 9ths/BAB +16.
Swapping in sha’ir for sorcerer allows the middle two to get 9th-level spells.
Wizard with a Sword
Where “Wizard 15” probably is more like “Wizard 5, and a bunch of full-casting prestige classes.” The idea here is simple: improve your BAB, don’t lose spellcasting or have to burn too many feats. If you’re an elf, you actually don’t have to do anything but wait until you get sufficient BAB. Everyone else needs to use a feat on it, but wizards can trade Scribe Scroll or their 5th-level feat for it.
Note you can easily substitute any spellcasting class for Wizard here without any difficulties at all.
Jade Phoenix Mage
Wizard here can, again, be swapped with just about any spellcasting class, and you can easily swap levels in the base class for full-casting prestige classes.
This build has a ton to recommend it. You do (barely) manage 9th-level spells (note: a sorcerer base will not), you get BAB +16, and you get 8th-level maneuvers (you may have to delay your final level of Jade Phoenix Mage until 20th so you can actually select one).
Swiftblade
Wizard may be swapped with any spellcasting class that gets haste as a third-level spell (and gets access to it by 6th level).
This nets you BAB +17, 9th-level spells (barely; will not for sorcerers), and a ton of amazing class features, including casting-ability-mod-to-initiative, attack, damage, and movement bonuses, permanent miss chance, free Quicken applied to haste, Evasion, treat haste as Extraordinary (!), and an extra move or standard action per turn.
Swiftblade 10 is an interesting conundrum; you miss out on 9th-level spells, but get Extraordinary time stop. Words cannot describe how amazing that is. Generally speaking, 9th-level spells are better, but you’d be crazy not to at least consider giving them up for this.
Sublime Arcanamach
Gets 9th-level spells, Inspire Courage, Arcane Channeling, Divine Grace, and a whopping BAB +19. Silverbrow Human is the recommended race, for Dragonfire Inspiration. Snowflake Wardance gets you Cha-to-attack on top of your Cha-to-saves. Taking Martial Study, Martial Stance, and Song of the White Raven would be really cool if you can swing the feats. Unfortunately, the Arcane Channeling is only standard action attacks, which aren’t terribly impressive. Better would be...
Twice-Sublime Phoenix of Harmony
9th-level spells, 8th-level maneuvers, BAB +18, and Inspire Courage and Divine Grace. Leveling up to 11th level will be rough as a charisma-heavy wizard; consider sha’ir instead, or even sorcerer (note: sorcerer does mean “only” BAB +17), just so those middle levels aren’t quite so painful. Feat suggestions are the same as for Sublime Arcanamach, except you won’t need Martial Study/Stance. If BAB +17 is sufficient, consider taking two levels of sublime chord instead of the level in abjurant champion: the song you get at sublime chord 2 is very nice.