Guys, on a girl's body what do you prefer?

A flat stomach, that is not toned though just naturally flat (mine is, bc I am naturally thin, with a waist of 24 inches, like Christina Aguilera, Mya, Keira Knightley, Natalie Prtman) or a stomach that is toned (like Janet Jackson's or early Britney Spears) or a stomach that is slightly thick or bulging that is proportionate to the girl's body (like Marilyn Monroe, Kelly Clarkson's, ? Which is the cutest/iest to you?