Here's some good straightforward with some twisted evil:
According to Dr. Stone's Scale of Evil, where do various villains fall?
The Joker: 16
The Penguin: 14
The Riddler: 10? 11?
Harley Quin: 03
Two-Face: hm. A tough one (naturally); 13?
Scarecrow: 19 (psychological torture, that is)
Black Mask: 20?
Care to debate or expand the list?