By many women's own admission, there are hot guys who can have sex right away and there are not-as-hot regular guys, who need to prove that they're good relationship material before there's any sexual intimacy.

It then follows that casual sex is more likely to be fulfilling for men than relationship sex.

Casual sex is built on real physical attraction and passion. Women have told me they're more relaxed with casual sex guys because they have nothing to prove or worry about being seen a certain way. They can let loose and enjoy themselves. This kind of sex is also purer and less transactional. Alternatively, women can be trying to please the casual sex guy so he wants to become her boyfriend, so they go all out for him.

At best, relationship sex is equally good, but there's also a big chance it's gonna fall short or be a mechanical obligation.