I personally believe its females since (including in the animal kingdom) males are the ones attracted to the females and try to win them over. Meaning the fact girls are girls, guys are instantly attracted and drawn in while girls dont experience attraction instantly until there is an emotional connection.
That and the way relationships work (also in the animal kingdom).
males try to get with females until one accepts, the male then provides/ protects the woman and child, while the girl just looks after the baby and gets taken care of. The males also often risk their lives while doing this.
While the female is less attracted (obvious through the fact they aren't attracted to attractive men without an emotional connection) and gets taken care of all because its the males instinct to care and protect while its the female to nurture and protect the baby.
In my opinion this is clearly one sided and more beneficial to the females.
I'd be really interested in hearing girl's opinions.