Kylo is a fine choice. A bit weak early on, but his high HP pool, revenge-themed abilities that actually sort of counter Dooku (pull a counter with AoE, take damage below half without suffering the Jedi ability block debuff, use the single target active for huge damage and wipe him in one shot, crit or not) and ability to somewhat reliably heal block make him a good addition to an attacker-and-support heavy team. Essentially allows you to burst down crucial targets in one or two rounds for him, depending on if you crit, as well as the focused target's level of survivability (HP, resists, dodge, self-heal/regen procs) and even without needing the double damage bonus for low health.
In summation, go for it. :) Even if he's not crazy broken compared to some heroes in certain comps, he's extremely fun to play as. Especially if you plan on including a Vader in there sometime, despite his lack of ability to progress in ranks. Still pretty great base HP and utility at high levels and gear loadout. Not bad basic attack damage either, with an extremely useful ability block (helps keep Dooku stuns and Sidious or other AoE off your healers.)