What are the stat priorities and the caps for Blood DK Tank?

[NihilFTW]

The 1st question is in the title the 2nd is which part should I replace for 4/5 setbonus of t10?

[Asphyxiation]

The important stats are:
1. Defense up to 540
2. Spell Hit rating up to 9% (8% if you have Draenei in your party / 5% if you have x3 Virulence)
3. Expertise at least up to soft cap (26 afaik)
That's about it. Armor, stamina, strength and other stats will come as you reach best possible itemization so you shouldn't worry too much about them

[Qtinz]

Stamina all the way.

540 defense.

6% spell-hit with glyphed Taunt to never miss a taunt in a raid environment. I'd recommend 8% melee hit, though.

Expertise: Atm. there are no parries on Icecrown and the dodge cap is still not working correctly. My melee DPS classes are running 22 expertise and I haven't had a dodge in a boss fight in my last 15 ICC25hc raids. In my tanking gear my dk is running 31 expertise (http://wotlk.openwow.com/item=50730 + http://wotlk.openwow.com/item=51308 + http://wotlk.openwow.com/spell=53137). With fixed Expertise you'll need at least 26. And a lot more if parry is fixed too and parry-haste is working.

The 1st question is in the title the 2nd is which part should I replace for 4/5 setbonus of t10?

In my opinion there are only two viable options. http://wotlk.openwow.com/item=50640 and http://wotlk.openwow.com/item=49904.
I'd always take the helmet, because of

a) it grants a lot of hit and makes reaching the melee hit cap pretty easy
b) the T10 legs grant easy to get expertise (not very easy to get stat as a tank)
c) http://wotlk.openwow.com/spell=48792 benefits from the defense rating the legs provide

This is highly controversial, though. Many people prefer the crafted legs and you will be totally fine with them too.

[angrylol]

I use 11% spell hit, that is ±289 hit rating. There is no bonus 3% for spells(from boomie or shadow priest) on adds or when you pull, so abit more I think is just what tank needs. This is not "must have" or "best", but I prefer 100% reliability.

[Selaya]

7.2% of melee hit (thats 235 rating iirc) will cap your taunts with the glyph which by itself gives 8% of it.

[Nevim1]

Talking about Lordaeron server.
My main BDK is "Fofr", alt Fofrcz and I have never played an expertise cap, who teached you that ?!?!? a Warrior tank I suppose? :D
BDK is usually a main tank in most of the raids so you have to focus AGGRO + SURVIVE.
Good Blizzard creators gave you many def CDs to survive any Spell from the boss so the only thing you care is to survive also melee DMG from the boss.
MOST important stats are: ARMOR > STAMINA > hit > THERE IS NOTHING ELSE.

When you want to get to the raid, show them your GS spec, which is always the entrance card needed, then before the boss, switch to Armor gear and you survive.

[Royz]

540 def cap
8% hit. I dont use taunt glyph. Dk's have basically 3 taunts ( Icy touch, death grip, taunt) no way u will miss all of them
20+ exp u will get from gear. Might as well use 2nd gear equip with exp nonset for bosses with parryhaste. Hard cap for exp is 56