I think warriors will always be the best, by quite a bit, simply due to their obscene mobility and stuns. They also have better sustained avoidance and damage reduction than Blood Dks. AMS and IBF are nice, but really, who doesn't try and kill a DK with a silence.
I know you can Death's Advance while silenced at least. Maybe you can desecrated ground as well, that would be interesting, two PvP trinkets.
But, I still think Warriors will always be king of the rbgs. So many outs. DKs can still do it, but it probably won't be ideal. We were at least #2 when I got hero and it worked with me tanking, but any time I could go offense and have a warrior we went from like 90% to 99% win ratio.