Ultra Great Sword require a lot of STR, Twinblades requires a lot of DEX.
I've heard that DEX scaling is not as good as STR scaling, and am hesitating between leveling up to equip one or the other first.
My play style is to keep myself out of reach with a long reach weapon (currently a spear), wait for the enemy to attack, dodge, get one or two hits depending on the monster recovery time, and get out of reach again.
While trying (without required stats) the different weapon types, it feels like both the Ultra Great Sword (tested with Pursuer GreatSword) and Twinblades (tested with twinblades) have a long enought reach for me, and the attack time doesn't feel that different.
I have trouble finding out what to keep, since I want to do the most damage in my hit. UGS have a longer reach and raw damage, but on the other hands, the twinblades does multiples hits in one attack, and weigh much less, allowing for a faster recovery.
What would help me is a damage comparison between UGS and twinblades in the context of wait-dodge-hit tactics.
Best Answer
To be honest, as you mentioned, it's a choice between Tank or Rogue - two very different builds.
Firstly, as we all know, one thing to account for is damage received. Wielding a Ultra Greatsword is slow, allowing for enemies to get their hits in between strikes - so allowing for extra armour and health is important. This can also be done for the Twinblade, however, it's far more likely that this type of character will be more nimble, dodging in and out of the fight, so endurance, and a light load is more important.
Now, for the numbers -
Ultra Great Sword:
Let's use the Greatsword as an example. When Scaled to +10 you can get an AR of 400; but with the soft cap of 50 STR, and the minimum DEX requirement, you can get a total AR of 579. 629 with Ring of Blades +2.
In terms of DPS however, with a speed (measured by "BPM" or "Beats Per Minute") of 48-53 BPM, it is fairly slow.
Twinblade:
In all honesty, there are only two choices that benefit more from a DEX build - the Dragonrider Twinblade, and the Curved Twinblade; and to get these require a trade of a Dragonrider Soul to Straid to get the Dragonrider Twinblade, or to rank up in the Covenant of Blood, or purchase it from Wellagher in NG++ to get the Curved Twinblade, both of which are a little challenging.
The rest of the Twinblades are based primarily on STR, however, they have a higher STR/DEX balance than most other weapons*.
That being said, however - let's compare anyway.
The Dragonrider Twinblade has an AR of 185 at +5 (don't have the details for total with 50 DEX right now), whereas the Curved Twinblade has an AR of 170 at +5.
As for the speed, Twinblades technically have a much higher "speed", as they have multiple attacks in a single swing. For argument's sake, let's say 4 in an attack, but have a much slower BPS (only as much as 30 - but I am yet to accurately test this).
Comparison:
So, let's compare.
Base AR*APS(BPM/60) = DPS
All in all, they can be considered to be roughly the same. The numbers might look like they're enough to go off, but there is also Poise damage (The Greatsword can literally knock an enemy off their feet), or other effects, such as Bleed buildup (the Curved Twinblade has this feature, and can even be buffed for a quicker buildup).
So, I hope this has been enough information to answer your question, however, this really only scratches the surface, since there are multiple Ultra Greatswords, and multiple Twinblades, all with their own properties to compare.
POST NOTE: I'd like to say that a lot of this is based off bad maths and assumed values - timings using a metronome is always prone to human error, however, at this current point in time, this is the best maths I can provide
*Most weapons have one primary stat. STR, DEX, FAI, or INT. For Twinblades however, the idea is that they require STR to deal damage, just like a regular sword, and DEX to wield with such finesse.