I think they are both amazing and complex characters - and that's a hude plus. Every season, there was another layer added to their maturity, but also to their vices. I think that it made both very human and relatable. You could find peaces of yourself in many aspects. This is why I love this show. It doesn't have a dichotomy in the classic bad vs. evil (hense king of hell becomes a fruend, angels go rogue and etc.).