I was talking with a guildie today because I was interested to get back into tanking. He said that blood was good for raiding, but bad for 5 mans due to lack of aoe. He said frost was better for aoe/5 mans, but ended up as OTs because of the lower health pool.
I loved tanking as unholy. It was good for aoe, and had a fair size health pool. But after Blizzard changed Unholy Blight to deal with death coil, they eliminated a big influnce of my tanking.
Post your opinions, and if you are a successful death knight tank, please post your spec and rotation. Thanks