This kind of thing has been a debate ever since the most primitive man has seen a titty. Seriously, men tend to get really picky with their girls since we all obviously develop different tastes. Especially when the internet has made it quite easy for you to explore all kinds of things easily, everyone has been developing all kinds of preferences. This means that men have quickly developed preferences for different kinds of breasts, butts, hips, and whatnot. The only natural criteria that came on naturally was the one that comes to you on a subconscious basis. Wider hips meant a better chance for your woman to bear your children safely. However, men now tend to fetishize boobs much more often, and here you get to see medium sized boobs more than anything else. See them bounce up and down while the girls are pounded, see em groped n squeezed.