each race has its on pros and cons
I have an orc, I like orcs the best, the stun resistance helps me SOOOOOOOO much, especially when half the warriors in arenas are stormherald / deep thunder wielding asshats. It's also great against rogues in 2v2's.
having on demand AP is great too, especially when it comes down to you vs 1 of their players left... we're also getting another crit with axes, but that's not really great for arenas.
Taurens hp boost is nice, so is warstomp. the hp has never really made a tremendous difference to me when I play with my friends tauren warrior [he's mace spec, I'm sword spec] or when I play against them.
Warstomp helps, but in arenas you're never really going to get to have everyone bunched up [unless the team is terrible], but it's really nice as an interrupt for spells and slam use.
gnomes are awesome too, escape artist, being tiny and hard to click on at times is sweet.
Undead have the WotF which is nice, but not really necessary as a warrior... especially one that is doing pvp (DW AND zerker rage + trinket] other than that they suck.
trolls are the weakest of the horde for warriors... zerking is fantastic for casters [esp healers], but you're neither so meh.
humans are nice for perception and now +1 to crit with maces and swords - the 2 dominating weapon specs for arena warriors.
dwarves get stoneskin [no poisons, nice! and armor too]
NE's get shadow meld and a 1% dodge...
Draeni get a 1% to hit aura and a [weak] hot...
meh, take your pick.