From what I can see, the bear might be my best bet, though the death knight might also be acceptable. There are more cooldowns than I would like on the death knight, but it is better than warrior or paladin tanking from what I remember and the basic "rotation" is dead simple. I have no clue at all on the brewmaster style. My druid is my "main" so the bear would also be the easiest to gear up as I get drops when I don't have a greedy panda (like this toon) rolling against me ;-)
Note that this would be 5-man heroic and LFR tanking only, just for fun and to keep the game interesting. I'm not concerned with min maxing or whether one class or another excels at progression. I would probably go back and solo all raid content that is doable in LFR level gear.