Topic what is best pvp class?
There is not such thing called best class for pvp.
Try... Playing... a warrior....
I'd go with either rogues, mages or any kind of healer. Just because those are often the most frustrating classes to play against. Rogues and mages can easily control most of their opponents and if they truly want to get away from you they will. If you don't have bleeding effects and keep them up all the time there simply isn't a thing you could do about that.+
As for healers, many DPS expect to be able to kill them single handedly and get frustrated when they can't. So just thinking about how angry the guy who's trying to murder me for several minutes must be at times simply cracks me up.
Not to mention the joy I get out of rescuing someone who was about to die and denying the enemy the killing blow. Just think about those situations where you were about to finally finish an enemy off and then he or she suddenly jumped form 1% back to 50% hp and then to 100% before proceeding to destroy you.
Not sure if anyone else said this but, the best way is to level one of each class. Get used to the spells learn how they work. And after that, play a few BGs at lower levels to get the rotation right.
Then I would actually say, go Retribution Paladin. :D
'Cause it's not really about what class you play or what specc you go. If you know the classes perfectly, you know what the enemy will throw at you, and you will know how to counter it.
It's usually about what you bring to the BG, for instance you rarely find random Rets who throw you an offheal WoG (Word of Glory) in BGs even with their own health being pretty low, or cast HoP (Hand of Protection) on you when melees are hitting you hard or even HoF (Hand of Freedom) to save you from snares. But being one who does, or when you find one who does. That is usually a Retadin who knows what he/she is doing, and knows the class very well. :P
My tip is, try all classes, level them all. PvP with all. Duel people as much as you can, but be sure to try a retribution from level 1 to 85 in BGs. Once you hit 85, be sure to give it some time, til you feel you got the sufficent gear to compete. I would say atleast 4 K resilience.
Hope this helps. :D