DH or MK.
One on one the two are an even match, then the better goes to whoever has the best micro. DH does 30 dmg/s chaos damage, MK does 26 hero attack. In a 1 on 1 battle, the DH has the edge if it can get off one mana burn before avatar kicks in, and then it is a grueling match. The MK has low mana, wereas the DH has the ability to burn off mana, and dodge 1/3 of all attacks.
Meta is better suited at targeting smaller clumped units because of it's splash and chaos damage along with a high rate of fire, and immolation. In that case it is great to hit Air units (especialy Gargoyles or Flying machines trying to hit any of the DH supporting air) In that respect the DH is far more versatile a warrior and is far greater. Therefore it is the best.