If youre just doing dungeons it doesn't really matter as they can be cleared with 4dpsm but if youre looking for that "carry potential" then WAR has more than DRK as Nascent Flash allows them to keep another party member and themselves healed up, as well as equilibrium giving war great burst healing, if you know what youre doing most dungeon bosses would be soloable on either if everyone bites the dust, but when it comes to soloing drk has the edge because Nascent Flash has a targetting requirement. Both of them however should make dungeons go pretty smooth in general, both of them require far less healing than a pld due to nascent flash and TBN making them largely more tanky in large packs, and dealing way more uniterrupted damage, as well as having more cds in the case of WAR.