Well, they're fuzzy. And shouldn't be petted.
K. Happy holidays!
Oh, fine. Real things to consider. Let's start with some basics:
1. Interrupts and taunts cannot miss. Note that the interrupt attack (like skull bash) can miss, but the actual interrupt effect will never miss. This has been confirmed by repeat experimentation a ridiculous amount of times. This means that other than threat (and savage defense procs), there is no reason to gear for hit as a tank.
2. Parry haste does not exist for anyone. For players, for mobs, anyone. That isn't to say that mobs can't parry - or that they don't quite a lot - but it does mean that using expertise to get less of a chance of gibbage is a bit silly. Thus, other than threat (and savage defense procs) there is no reason to gear for expertise as a tank.
3. Haste improves the speed of autoattacks for bears. This improves rage generation slightly, but only slightly. It can slightly increase the number of SD procs you get, but only barely. In theory it will let you maul more, but not a whole lot more; mauls are usually a function of damage intake, not white attacks. Thus, other than threat (and savage defense procs) there is no reason to gear for haste as a tank.
4. While vengeance improves savage defense, it does have a fairly high ceiling. For most bears this means that they are not vengeance-capped (where vengeance is equivalent to 10% of their health). Which means adding more health does not improve mitigation; just because you have more health doesn't mean you'll be hitting for more via vengeance. This will vary between tank to tank and encounter to encounter; I expect that as you get into heroic raids you'll start pushing the limit of vengeance stacking and it'll improve again. But for the most part, stamina doesn't help mitigation (stopping damage intake), it only improves survival.
5. Most of the time stamina isn't helping survival all that much. We are at the point where effective health is not nearly as relevant as taking less damage and being smart with mechanics. Tank healing is pretty simple as long as the tank doesn't screw up a mechanic. Tank survivability is quite high; I've been able to survive for 20 seconds without external healing - and that's with a mishmash of tanking and dps gear. There aren't that many fights where the tank is going to be taking a ton of damage, at least not on normal modes; Heroic Nef hits for about 70-80k on a tank in normal 25-man, and he's by far the worst offender. What this means is that stamina past a certain point is just not that great. Gone are the days where bears got way more multipliers for their stamina, and gone are the days where a stamina gem gives 1.5 times the benefit it does to other tanks. Stamina is not the be-all, end all of a bear's use.
What all of this means is the following:
1. For heroics, don't bother stacking stamina unless your gear level is very low (like, just barely able to go into a random). Stack agility and reforge the highest value to dodge.
2. Understand the fight and be able to redo gear cheaply. Flasks for agility are good (especially since the stam flask isn't as good as it should be). Swapping cheap enchants is another idea. Use justice points to buy second sets of gear and redo them for stam and agility.
3. Threat is largely unimportant right now. If you're really concerned about it chances are you're doing something wrong; on a single target fight it is very, very hard for dps to touch you past 10 seconds.
4. There's no reason to worry about misses on important stuff.
The end result of all of this is that agility is Very Good. Mastery is Good. Crit rating is Good. Stamina is Good (to a point). Dodge (which gives about 50% more dodge% than agility does) is Good.
Hit, Expertise, haste, strength, AP? All meh.
Which, interestingly enough, is very similar to what the priorities are for cats. Other than dodge, that is.
And armor. Oh yeah, armor! If you are going to go stacking effective health despite what others are saying, keep in mind that armor improves both survival and mitigation. Also keep in mind that the best heroic armor trinket - Heart of Thunder - has worse armor than the worst old trinket you can buy - good old Glyph. If you can get your hands on a Petrified Twilight Scale it's well worth it.
Some other fun tricks:
1. Entangling roots is awesome. You're the only tank out there that has not only one CC but two. Both are situational and not perfect, but both are great and are good in a pinch. Know how to utilize them in various dungeons. Get used to them.
2. Remember that you can shift out of snares. There are a TON of snares in dungeons now - Ozrek's paralyze is a good example. Instead of waiting for the damage to free you, why not free yourself?
3. Get used to Line of Sight. You don't have an easy silence but you do have a ton of LoS abilities. This helps a ton with caster pulls. Otherwise casters should almost always be CCed; you can take a lot of physical punishment but don't have the control of caster that other tanks do.
4. Remember that skull bash is a short charge, too.