As someone who's in great shape, i'll say mouthpiece, and here's why:
If you're in really good shape, that will actually make a lot of females insecure. Unless she's in really good shape herself, she's gonna be insecure of the fact you're in such good shape. She'll feel fat, she'll feel like a lazy slob, think "why does he like me?" or she'll think you're a player.
Now we know most girls(and most people in general) are

, so they're used to other

people. So if your mouthpiece is good, then you don't have to worry about making them insecure and being scared off.
I've seen some above average looking females with chubby dudes or scrawny dudes.
Now if we're talking about a 1 night stand type of thing, then it's physique all the way.
