The reality is, all women like both types of men, but for different reasons/goals.
Regardless of relationship status (married, single, whatever), women of all ages are sexually attracted to "dangerous/bad guys"... not all necessarily act on that instinct, but they still feel the attraction. Since prehistoric times, bad guys are the ones who would be the best at hunting, defending against attack, and generally athletically/physically superior in general. Therefore, she has a desire to mate with him to pass on those superior physical genes in her children... it's just nature.
At the same time, women also like to have someone around who will provide a stable financial situation and who they can feel safe around. However, that doesn't mean they're sexually attracted to that guy, but they will sometimes trap a "nice guy" into that friend-provider role. Once married, the guy is locked in and the girl doesn't have to put out, since she gets half of everything if he divorces her. Meanwhile, he's pumping $$$ into their house, cars, etc, giving her a stable home. So that's a win for her, though she'll end up looking for sexual satisfaction elsewhere.