User blog comment:ImperiexSeed/The oldest being, archangel or leviathan?/@comment-4393153-20120517202306

I'd say that the leviathans are stronger, one of them (Edgar) said that leviathan beats angel, and the archangels are angels, just stronger than the generic brand. Also, when people way the leviathans aren't strong becuase it took them so long to break out of Castiel, remeber that at the time Cas had enough power to kill Raphael with a snap of his fingers. Raphael isn't a strong as Michael, but he's still in his league, so Castiel was way above the paygrade of the archangels, and the leviathans still forced their way out of him (after assimilating all of his knowledge, which is extsensive). Also, Castiel was confident that he could take on Death at the time as well. I'd say that they are stronger, they just don't have the same number of different abilities.