Guys have better odds of getting into a relationship with a girl who is better looking.
Girls have better odds of getting to hookup with guys who are better looking.
This is because guys are more likely to lower their standards on sexual attraction if they are getting sex without having to work for it or make a commitment. However girls have HIGHER standards for casual sex because if they are going to give away free sex without expecting commitment then the guy has to be really hot by her standards for it to be worth it.
Then for relationships guys have higher standards for looks compared to their hookup standards while women are more forgiving and more willing to date guys they aren't super attracted to, assuming he is reliable, financially stable and has a good personality.
I see it a lot around me: pretty girls with fat guys mostly. I see a lot of fat girls who are single. And the fat girls who do have boyfriends usually have boyfriends fatter than them. Sorry for all the "fat" mentions. I think it's just our culture here in the Philippines. It sucks but that's what I've observed. People focus on weight and body size way too much.
I think it's easier for guys to get a better looking girlfriend. Mainly because I think most girls are more open to dating different types of guys. Whereas guys are more strict in what they see as attractive. At least that's been my experience.
Unfortunately I fit a very narrow portion of the population's attractiveness type. :(