For me, it's mainly about the final look and the attitude of the woman.
While there are women with large naturals who are pleased with their look, there are other women with large naturals who hate the attention, complain of back/shoulder pain, and the only surgery they're thinking about is a reduction. These women will be more likely to dress them down, cover them up completely, slouch, be stand-offish, etc.
Conversely, women who get a breast augmentation do so because of the allure, and typically do so after long evaluation. (Not all end up happy, due to the surgical experience, the surgeon's attitude, etc, but that's another story.) These women will be more likely to dress them up, stand tall, etc.
There are many other factors worth considering, but since this is but a simple and straightforward poll, then we can answer in a vacuum as well.
So my "all other things being equal" answer is that I like both, but have leanings towards augmented, for the reasons stated above.