I don't like it when people compare units in a simple one-on-one scenario. You need to consider each unit and their abilities in conjunction with other troops (taking into account various spells). Yes, I agree that Archangel and Black Dragon are among the best, but Black Dragon looks good with Armageddon, and Archangels will be important if you simply need the first turn (for example, to protect archers from Black Dragons). You can list options for a long time, but comparing who can kill whom faster in a one-on-one fight is, in my opinion, not entirely correct.