I have overs, and i thinks it down to what the surgeon says. i did want really fake looking round boobs, but mine are quite natural looking. You can tell their fake without clothes on though, as very round and pert. But with clothes they look really natural.
However, my friend had unders, she had hers done in marbella, and had no chest at all to start wth, hers have been in for nearly 3 years now and they are solid!! and very stuck on. they do not budge at all. mine wobble. I think i do prefer my friends boobs as they so hard. but she had to have unders as she didnt have enough breast tissue for overs. Alos if you have overs and dont have enough breast tissue to hold them you can risk ruputuring them. But the surgeon will decide for you. you usually find girls with A cup boobs need unders. but usually b cup and more overs. xx