I am playing a warpriest now, and have for a few sessions.
He is ok, I guess, but nothing special.
I like the e-Thief a lot, and my current PC is a Thief. I like being able to reliably hit & dish out tons of precision damage, although he really sucks vs minions. Second would probably be the Knight, although I like the old 4e Fighter too. The old 4e Rogue was rather weak by comparison; as a melee Striker too squishy, as a ranged Striker unable to reliably get CA.