There has to be a base level of attraction. She doesn't need to be close to perfect, but i don't want to be with a woman that looks like Freddy Krueger even for a short term relationship. In that aspect I admit looks are most important.
Once she has met my bare minimum standards in looks then her personality starts to get judged, and can help or hurt the image I have of her. At that point, her personality starts to become more important than her looks, even if she isn't as physically beautiful as a another woman.
Both. For sex, looks is the only thing that matters. For relationships, personality matters the most, but looks matter too. You can be extremely hot, but a bitch, and no one will choose you for a relationship. But you can also be amazing, but as ugly as the back of a fridge, and most guys won't choose you either.
If I'm not attracted to a girl, her personality isn't going to change my mind. If I don't like a girls personality, but I find her physically attractive I may want to have sex with her but I don't want a relationship with her.
Both, if I don't want to have sex with her, then I probably won't date her. However, personality is important too. If she is all looks and no personality, it will just be hanging out with a beautiful painting. I'd rather just get a beautiful painting then and not have to put in any effort, lol.