Pam and Leslie are genuine sociopaths and are the only ones who have actively tried to kill others without hesitance or regret.
Then you have a huge power gap.
Harley's insane, but this is probably one of the more toned down versions of her. She's basically just your standard troublemaker, although she has used threats of violence, which pushes her to third place.
Catwoman is a klepto, but that episode where she teamed up with the other girls for a heist proves that there's some good in her.
Giganta is just a meathead bully, so she's more bad than evil.
In last place you have Carol, who's more or less well-adjusted outside of a fanatical yandere obsession with Hal which drives her to criminal temper tantrums. Really I'm not sure why she's even a part of the team considering her only motivation seems to be winning Hal's affections.