Me, ideally I'd want a virgin. If she's been with a small number of guys, I can overlook that. However, if she's been with many guys, I couldn't have a serious relationship with her, it would always be in the back of my head that many other guys had my girl and it would always bother me.
Also if she's ever done porn or been a hooker, that's definitely a dealbreaker. It shows a willingness to disrespect her body for money.