For lower levels Balloons can be a great alternative to dragons, but they are not as good at higher levels because they can be killed easily by Archers. Apart from that Wizards can completely demolish a Giant and Healer strategy with their intense splash damage and they can hide behind walls. Archers are good in the fact that they can be protected by your walls while dishing lots of damage. Healers can now no longer heal buildings and can only heal heros or cc troops. Though in certain scenarios this can be useful, such as if you want to try Super AQ on defence, but in general healers are not good for cc.
Make sure to position your clan castle in the center of your base to protect your troops from easily being drawn out and killed. Keep in mind that if you use your clan castle well it can completely change the outcomes of defences!
Usually a dragon is one of the best. Wizards are very powerful as well. Valkyries are somewhat rare, but are good thanks to their spin attacks that can destroy troops very easily. My personal favorite are witches, because they are essentially a permanent skeleton trap. Overall though, almost any troop will work fine, but the ones with high damage and health (pekka, dragon) are generally good in most scenarios. The ones with high damage to space ratios or ones that can fly (wizards, minions, balloons) are better in my opinion, but can be very easy to kill with a lightning spell. I've never had one of the tank units used in a defense yet, but I would think that the lava hound and, to a lesser extent, the golem would be very good, but only if they weren't lured out. I consider witches the best, simply because after a few sets of skeletons have spawned, they start being very space efficient for the amount of troops they produce.
EDIT: I forgot about a few troops. Obviously, wall breakers are the worst, followed by goblins. Barbs and archers are the general filler troops that preform fine for the cost, but don't really stand a chance against their more expensive counterparts (minions, wizards). Healers are good because they can heal troops and buildings, but require units with at least a decent health pool for them to be worth the space. Giants are mediocre at lower levels, but even at high levels when their damage and health are quite good, they are still very easy to lure and kill with only a few wizards unless they are partnered with a healer which boosts their value considerably. Last but not least, hog riders are an interesting unit. They are stuck in the middle ground between tank and damage dealer, but are outclassed because of their stats to space ratio. Valkyries are significantly tankier, deal more damage, have an AoE attack and only require 3 more spaces. This is mostly due to the hog riders ability to jump over walls. Their stats have been weakened to compensate for this extremely useful ability, but on defense all units are given this ability, essentially making their biggest advantage nonexistent.
My Personal Ranking:
- Witches
- Valkyries
- Wizards
- Balloons
- Dragon
- Minions
- Pekka
- Hog Riders
- Giants/Healer
- Lava Hound
- Archers
- Golem
- Barbarians
- Giants(without healer)
- Healers(without tanky troops)
- Goblins
- Wall Breakers
Best Answer
With a dragon attack if the clan castle is in the center, not luring the troops is the best way to go. When the dragons lure out the clan castle troops, they get pulled into the center allowing for much better destruction and a much higher chance of destorying the town hall. Clan castle troops are usally unable to do anything close to what will endanger dragons.
First of all, ballons, barbarians, valkaries will not be able to attack the dragons. Archers will all cluster into one group during the time when the dragon charges for his attack (which will wipe out the whole cluster). A pack of high level wizards will be the most danger for your dragons. A level 6 wizard has 270 dmg per attack, times 5 for TH7 and 6 for TH8, would be 1350 and 1620, but dragons have at least 1900 health. Though this cannot wipe out all your dragons, it will still critically injure them. But this is in the rare case when the opponent have all lvl6 wizards and all your dragons are clustered together.