The tank classes are currently very well balanced. Each one has it's situations where it might be a little more useful than the other, but both can do all the content as MT or OT. The general idea is if the fight has more consistent dmg then Paladins shine but if the fight has spike dmg periods Warriors shine. Both just as useful than the other. Really depends on your group makeup how you wanna go. Play whichever one is most fun for you.