With the current racials (not the revamped ones blizzard is talking about for cataclysm) orc is looking to be the best for PvE.
Troll is currently best for PvE for it's haste rating racial right now.
Undead and Blood Elf are your choices for PvP. Wotf is imba but a second silence isn't half bad either.
And if you've ever went back and done Shadowmoon Valley dailies for your netherdrake, you will realize that red orcs are the best mages for tier 8 design-wise. <3