Srsly guys, stop trolling him. He's new to the bracket, let's atleast be honest.
All these guys saying hunter, paladin and rogue etc. they are just trying to get you to pick the wrong and under-powered class.
I have served this bracket for a long time and I've given many advices (see my postcount) so I'm not telling BS or anything.
For pure and insane dmg: Warlock, the nasty crits that appear when speced in Destro can hardly be beaten by any other class.
For survival + decent dmg: Resto Shaman, having earth shield grants you alot of mobility and on top of that you have a powerfull healing spell. Whenever you need to assist your team with some dmg, just throw one or two lightning bolts.
Good mobility + good dmg: Arms warrior, just try to get as much crit as possible and you can nuke any target down (even a insanely OP prot warrior). With your charge-ability the mobility should never be a problem.
For FC:ing: Prot Warrior all the way (especially when solo-queueing) you can last for DAYS man, just be sure to not run into a group of 7+ of the opposing team.
You are very welcome for this post, I put pretty much effort in trying to make a good over-look for you, now it's up to you to decide which class you want to play.