Are you talking to the picture on your username, because it seems like you are older than the age next to it. Either way, I'd have to see a picture to fully get an idea of what you are referring to. I don't really care for the skin colour that never really matters to me, all colours are good but it's the attitude and lack of self-confidence that is off putting to me. I personally like small breasts. And for what the other girl is saying, there are certain guys that like skinny women and also depends on what that guy's definition is of the word skinny and how he relates it to his taste in women.
I call bull shit on that perspective. The skinny girl, in my opinion, is more attractive because of the whole package. She has long hair which men like and boob size is not deal breaker. Most guys want a girl who has boobs and somewhat proportional to her body.
I think overall the light skin girl is way more bangable. Just because the darker one has bigger boobs doesn't mean us guys are automatically going to prefer her. I consider other factors, like hair length, weight, curves. I don't like short hair on girls at all.