I would try Warrior. It has a simple rotation and mainly consists of hitting buttons on cooldown.

I don't find Paladin that difficult, but I know some people that do. It has a strict rotation that doesn't vary so it's mainly memorizing what order you need to hit things.

I find Dark Knight and Gunbreaker have a few too many buttons, and Gunbreaker can be a bit weave spammy once you get Continuation.