First off, this is the list of responses overall:
It's an interesting spread. No one would ever use the balebrew trinket on KT, no one would use the heart on Hodir, no one would use Juggs + Balebrew on Anub, and no one would use glyph on mimiron. Interesting.
Here's what I either have chosen or would have chosen:
Boss 1: Kel'Thuzad (25-man) tanking the adds (at T7 levels of gear): I'd go with glyph and Black Heart. Huge health is nice on this, but not essential, and while you hit SI at the end this can actually hurt you if KT picks that moment to freeze you in a giant chunk of ice, as it does a percentage of your damage. Armor is awesome here, as it works against multiple mobs well and it deals with being stunned/frozen. I would also want an extra CD just in case, and glyph is great.
Boss 2: Hodir (25-man) tanking the boss at just starting T8 levels of gear. For this, you want a fairly large chunk of stam. I didn't mention, but I assumed you'd be one-tanking it. If that's the case I'd go with Juggernaut and Black Heart. For a bear, two stam trinkets (even at barely T8 levels of gear) is going to put you well over the frozen blow limit for stamina, so you don't need raw stam only. Black Heart gives stam for the frozen blows and gives armor for when he's not.
(bonus: does this change if you're trying for the hard mode?) Yeah, and as many alluded to chances are you don't need the stamina trinkets and are going for minimum healers, so DM:G gets the nod here - as does some other threat trinket, most likely. Or an avoidance one. Given the choices the best 'threat' trinket is likely the balebrew charm. :)
Boss 3: Heroic Northrend Beasts (25-man) tanking Gormok with one other tank, then tanking the stationary worm, then DPSing on Icehowl (at barely T9-levels of gear). This one was surprising to me, as while almost everyone picked Juggernaut, very few went double stamina. That's what I do, by the way - I go Juggernaut + either Heart of Iron (what I did to start) or Black Heart (what I do now). The extra CD from Heart of Iron was too good to pass up. On my first kill tanking it I went Defender's Code + Heart of Iron to get the extra CD, but it wasn't reliable enough and would lead to my death anyway.
Anyway, my experience here is that more than anything else, raw stam is great.
Boss 4: Heroic Anub'arak (10-man) tanking Anub'arak (at T8-levels of gear) This is another interesting one. Everyone picked glyph, and it was the only unanimous pick of the whole test. But then choices were between Black Heart and DM:G. On 10-man, I went with Defender's Code and DM:G to start, but with the nature resist strat I actually went and equipped more stam, going for defender's code and heart of iron instead. Now that I'm doing it in 25s, I'm using glyph and juggernaut. The reason this works is that I'm getting rid of stamina in other ways. And the cooldown from juggernaut is useful, even though it heals; damage can be very rough.
The way I justify this is that I'm losing about 8k total health in using the other non-stamina trinket, the flask, and the various enchants. So I gain a bit back. So far, it's worked out ok.
I'm not a fan of DM:G on this because the worst case doesn't allow you to block and DM:G doesn't have an on-use. Dodging is good, don't get me wrong, but the thing that kills tanks is unlucky melee+slash+ leeching swarm more than anything. And since you're stunned, the main way to deal with that is by armor and stamina (and resistance).
Boss 5: Mimiron (10-man) tanking phase 1, then tanking adds in phase 3, then tanking all parts in phase 4. Again, most people picked Juggernaut as the first trinket choice. Many picked Black Heart, but that was puzzling; what actually hits physically hard on this fight? The assault bots don't, the boss doesn't; the dangers are almost entirely magical. I was expecting more Balebrew charms. For the record on normal mode I just did this with HoI and DM:G.
(bonus: does this change in hard mode at all?) Yes, it did - I went pure stamina and would do so again, so that I could hopefully survive the plasma blasts. It's tough.
Onto the comments:
Anon - the hydross trinket didn't have an internal CD, but it didn't proc all that often. I had an uptime of about 50%, give or take. Which makes it a bit less valuable than Glyph on the normal case, but it's not predictive and not on demand. It's kinda meh, but if you want to maximize armor no matter what? Probably a decent idea.
Frederic, Edward Nigma's wife is totally awesome as an answer.
dtc (and others) - I didn't put Heart of Iron on there because I wanted y'all to think a bit. Namely, is 170 stamina without an on-use good enough? Otherwise the answer is almost always "Juggernaut + HoI" over and over again, and that's boring.
Liz - RNG is a bastard on beasts, but RNG is really an illusion. The only really dangerous times are on impales, and you know exactly when an impale is going to hit, without question. Time your CDs (and use external ones) for these, and you will be golden.
As to Beasts and dtc's question, we do use only two tanks on beasts and so far it's been fine once we worked out a few kinks. Our rotation looks like this, kinda (from memory, so forgive me if it's wrong)
I start. Note that 'impale x' means 'have CD used for impale x', so if it says barkskin on impale 1, that means that barkskin is up in time to eat impale 1.
impale 1: barkskin
impale 2: trinket CD
impale 4: warrior taunts
impale 6: trinket
impale 8: I taunt, barskin
impale 9: GS
impale 10: SI
impale 11: warrior taunts, LS, I get BoPPed
impale 12 (if it happens): Shield wall
impale 13: PS
then warrior gets bopped.
Nowadays we don't get to impale 12 unless we got very unlucky on snobolds.
It is a shitton of damage, but it allows for faster DPS on all three phases and is fairly easy. With this rotation down we're no longer getting gibbed randomly due to tank death; the only issue is if snobolds decide to go kill nothing but healers. That's basically the only RNG part.