My two cents. I have a pally tank and now I have a bear tank. The pally, does avengers shield and consecrate and he has aggro for multiple mobs, the bear does Faerie Fire to pull (or Growl) and then once the multiple mobs come to him he has to spam swipe a couple of times to establish aggro. After that both are very similar, a bear can really just spam swipe and hold aggro in heroics (as long as the group are hitting the target you are on).
Of the two tanks, bear scores more points with me for chain pulling, they can run through mobs swiping as they go and pull aggro, paladins have to drop consecrate or avengers shield which have cooldowns that make it slower for them.
Overall I think both are VERY easy to tank with, now if you want harder then look at a DK or Warrior, much more micro management involved in their rotations to keep threat.
Have fun