Hmm...I'd have to say Machinist, Summoner and (atm) Paladin.

Machinist, because it makes me feel like it doesn't do any damage, and the skill animations are boring. It has no feeling of "impact".
Summoner because DoT & pet management. And the rotation is utterly confusing to me. I did level as SCH for the most part though.
As for Paladin, flash is shit. It does no damage, and has no visible enough range to see how far it reaches. Like with Machinist it feels a bit lacking in impact on mobs. Mind you my PLD is only in her low 30's atm so I hope I will like it more later on. But atm I loathe it.