Its never hands down anything.. druids (get ready this is the biggest plus for 19 druids premade/wsg/arena) cant be CCd. Thats the big one. Cant sheep, cant frostbolt, blah blah. One quick shift and its over. Thus druids have amazing mobility. Throwing hots and then shifting out and LoSing with an OOM stick to get mana back is amazing fun. Throwing roots to keep a target in place so the rogue can get to them is a lot of fun. If you are horde, war stomp = another stun/silence. If you are alliance your instant vanish can be amazing. The list goes on.
Priests...druids.. doesnt matter. If the player is good then you can excel. Its never hand down anything.