For me saying a guy is handsome is like calling a girl pretty. It's purely a looks thing, but it's the nice way of saying it. Like pretty is the nice way to compliment a girls looks opposed to hot or sexy etc. I call him beautiful sometimes, he isn't the biggest fan of it, but I only do it when I want to describe him as a whole and that he's just a beautiful person. I wouldn't say it in public or anything, it's just something for him because he is one and he doesn't tell me off for it - but that is a compliment for your inside as well. To me, as I said, handsome is just looks and guys seem to like it.