I think I mentioned it before, but I've got a character for each available class. Jedi Knight was great, and I really like the Defense build Guardian. Yes, that's the "tanking" build, but the "survivability" is AWESOME for any mode of play, especially for solo and group PvE. I'm "learning" to love Defense for PvP, though you have to take some time to learn your role. Speaking of which - I did a 4v4 warzone deathmatch last night, and we rolled the Empire, 2 rounds to 0. NO deaths on my part.
That said, I still like playing my Trooper in PvP more.