Either Donkey Kong Country 2, Dungeon Keeper or Warcraft 2. I see no reason at all for a remaster off DKC2, it is largely perfect as it is.
It would be neat to see a remaster of Dungeon Keeper but I am certain that there is no way they could ever remaster today without ruining the artstyle. Same with Warcraft 2, that one could probably have its gameplay improved as well, but there's no way I would trust Blizzard with that.