The biggest difference between tanks at the moment is not cooldowns, class or spec.

The biggest single difference between tanks is whether or not they are jewelcrafters. Every tank that I check the armory for that is in a very serious raiding guild is a jewelcrafter, because it is mandatory. I know that we've had this discussion before, but it is bordering on game breaking at this time.

I would propose that two things are done:

JC gems no longer be prismatic. This is the largest issue of overpoweredness. You can pick up socket bonuses for absolutely free and hit meta gem requirements without a concern.

Figurine: Monarch Crab (http://www.wowhead.com/?item=44063) needs to be made BoE. It's too large a benefit to have the best in slot trinket currently in game to be available to just one class.

I know this has been brought up before, but I feel like we need to bring more attention to the issue. And here's the thing: at one point or another, it will be fixed. I'd like to save myself, and everyone else, the hassle of rerolling jewelcrafting right before Blizzard decides to nerf it.

If I were making this thread, I would spell out the maximum tank benefits you would gain from each of the tradeskills and give the other posters a chance to comment on whether those benefits were so extreme that tanks are pretty much just going to all pick the same two of them.