Not all women ovulate. If you do ovulate, however, that could be part of why you keep dating bad boys. Even if you're ambivalent or uninterested in having children, ovulation hormones actually can cause you to mistake bad boys for good baby daddies.
According to a study published in the Journal of Personality and Social Psychology in 2014, ovulation hormones lead women to view "sexier," more "alpha" men as better potential mates and fathers than their less sexy, but obviously more dependable, counterparts.
Nice guys are too nice. No one can always be that nice unless they're a saint. They are busy being nice instead of being real, and women instinctively don't trust that. Bad boys "keep it real." Nice guys don't want to upset the apple cart.
No one respects a doormat. Nice guys don't set boundaries or make any real demands. A bad boy doesn't let a woman walk all over him or control him. Women can't respect a man they can control. No respect equals no attraction.
Most people lead boring, predictable lives, so they're attracted to people who are exciting and a bit unpredictable. Bad boys are always a challenge.
Nice guys are never a challenge. Predictable plus no excitement plus no challenge equals "I prefer a bad boy."