Superman hands down though what he did to Tim was more... disgusting and despicable since it was explicit child torture in a animated film.

The Superman one's description alone just pushed me over the edge. Like, f***ing hell, Joker...-

It was actually difficult, but considering Superman never came back to the light or to his senses, and that he has become very irredeemable even with his love for Lois, it has to be him