I agree that with having 2 males, your best bet for canine harmony is with a girl.
However, I really do think it depends so much on the individual dog. My mother's female BC is incredibly, well, for lack of a better word, b*&chy, and does not accept any other dog except for my submissive male, Tipper. Tipper accepts any and all beings, canine or human. Jenny, obviously a female, also is accepting of everyone, canine, feline, and human. So while your odds are better with adopting a female, I think it does really depend on the dog.
BTW, she's absolutely adorable!