DEATH KNIGHT COVENANTS BEST CHOICE

Currently Kyrian seems to be a strong ST pick for all specs, and Venthyr is in a similar position for AoE. Necrolord is a bit of a weird one atm, since it's certainly stronger than it was before, but it seems to be much more useful for Unholy than it is for other specs. That said, if you plan on PvPing Necrolord will likely be the clear winner.

UNHOLY DEATH KNIGHT

BLOOD DEATH KNIGHT

FROST DEATH KNIGHT