I don't think there's much of a difference as long as you get him/her neutered/spayed...Some people on here say that females are the sweetest, some people say that boys are the sweetest. I think it depends on the personality of the actual dog. I have a male yorkie so of course, I think he's the best, but I just recently got a female maltese, I think she's awesome too.
My advice to you is to get the dog that you fall in love with regardless of male/female. Just get the one that melts your heart