Their dps and tanking are equal on terms of difficulty, but I think paladins have a slight advantage over us. I don't know what else to say. I've just become used to playing a Warrior.
Bear in mind that this is from the perspective of someone who plays largely solo or with a few friends. If you're a raider, for example, the offense/defense shift plays a much smaller part, and may not be enough to sway you either way.
The issue with ret isn't it's numbers, but it's playstyle. It plays closer to a rogue than a warrior, with it's dumbed down combo point system and 'slice'n'dice' buff upkeep. Some people don't mind it, but it made me quit my paladin and try a warrior in cata. After years of being able to keep a wider view over the combat because your damage abilities were very simplistic, and being able to dispel/buff allies fairly easily for the same reason, cata had you suddenly micromanaging a short duration buff, watching for multiple procs and counting combo points, and took away the important part of cleanse, the remove magic. You have to do a lot more, but the damage isn't any higher than what you had before, and it has a clunky, disjointed feel to it now.
Warrior on the other hand, plays a lot more smoothly, especially comparing ret to arms. You only have one resource to worry about, only one proc to keep an eye on, and don't have to keep a short term buff up the whole time (other than battle/commanding shout, but it's 5 minutes, not 15 seconds). Not to mention that both arms and fury are higher DPS than ret, average player versus average player.
If PvP is a concern of yours, all I can say is that PvP on both classes was bad enough in cata to make me not even bother with it this time around. Warriors are supposedly pretty good right now, but they were supposedly pretty good in the beginning of cata too, then they kept taking arrows to the knee, and eventually they just sort of lay there like a bloody porcupine. That may or may not happen again, but you should be aware.
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