Warriors will be slightly better technical tanks come the xpac from a couple of new AOE abilities, but paladins provide more group utility. Unless you have another paladin as your healer or something, running with a pally tank giving out kings and auras to your group will make you a lot stronger than a warrior would overall. Also, the paladin's pulls are SO easy with just tossing out a chaining shield and an AOE consecration that stays put so that even if you miss with it inititally, mobs who step onto it still get hit.

But if you got a pally healer, go for the warrior if it's a raiding main. Just run the warrior in and build aggro for a little bit before DPS.