I agree - the flat version is more aesthetically pleasing because of how it actually gives balance to the rest of her body.
That said, I've always questioned the physics of phenomenon like this - even when assuming that such a chest growth is achievable overnight, I'd question how the girl would even be able to stand, since it would be as if she suddenly put huge weights in front of her. Her spine/back/shoulders would have taken quite a while to be able adapt to those mammaries, especially if she was accustomed to nothing at all.