I mainly play thief and mesmer. The "highly mobile - stealthy' combinaison makes up for a fast paced gameplay, especially in PvP, and I really enjoy that.
Not a big fan of the revenant and the ranger though. Can't exactly say why for revenant, but for rangers, I feel like their utility spells are all really "meh" and I don't like having a pet following me around.
What about you ?