I mained druid and I'm going to do it again. Everything that's bad about druids in raids/PvE in general is basically the opposite in PvP. If you care about that sort of thing. Moonkin can fucking 2shot people in wsg pretty easily with some gear. Cat can certainly hold its own in pvp, in raids it's alright but you're probably going to be at the bottom and you're only there for Leader of the Pack. Bear is pretty good 5man tanks believe it or not. I mean I'd rather take a warrior but bear threat/damage is really high. I wouldn't expect to tank many raids until deep into the games life cycle though.
Resto is good all around, people talk about it like you're at a severe disadvantage when playing it but I never found that to be the case for myself. Or the healers I was playing with are retarded, I don't know.
Flag running is my jam and all 3/4 specs can do really well at it but resto/bear is your best bet. You can kite anything in the game and with free action potions you're quite literally unstoppable.