At this moment, and what has been the same for a while at the moment – Arms is used most for pvp since it there is less rage required for your burst dps (making it able to play in defensive stance for example).
On the other had, it depends on how serious you would like to play in arena’s and RBG’s. I don’t think people use a lot of dps warriors in RBG’s, but they are pretty handydandy flag carriers in prot-spec.
But at the end of the day, just play whatever you like to play (unless you are aiming for high rated pvp.. ;))
thought id throw in my 2bits. i dont mind Arms warior for arenas.Although i am usually the first in group killed, when you pop your cooldowns ,you can do amazing burst. Most of the time you can do enough damage for your partner to quickly burn them down. I have just started to arena full time,but i can honestly say i love the arms warrior.If doin 3s an o/s heals is your best friend….pop and kill
Fury and Prot are both wicked if u just think outside of the box a little. Since the pvp resil/power changes in 5.3, both of these specs are alot more viable if u use the isle of thunder pve 2piece set bonus for either spec. Fury gets the ability to enrage off of regular attacks, and finally with prots 2piece pve bonus your shield slam/revenge hits have a 10%chance to proc vict rush/impending victory, which means at long last us warriors can go toe to toe with a geared blood dk and actually have a chance at winning (or forcing a stalemate). Now everyone thank blizz for fucking up our pvp and letting ppl in partial pve gear come kick ass lol.