Full head of hair is my preference. But I must say, there are some bald men who are very sexy. The guys who are semi-bald and trying to hide it under a ball cap all of the time...no so much. Keep it short, and do not do a comb over. It is what it is.
A full head of hair is definitely my preference, but that doesn't mean I couldn't find a bald or balding guy attractive. Not that, at my age, it's something I really have to think about.
Some guys can pull off being bald better than others. Certain guys might look best shaving their head when they begin to bald, others may look better keeping the hair they have. Girls will be attracted to all sorts of things. I think the best thing anyone can do is try to find the best look that suits them individually.