I agree with those that say personality is more important than gender. Everyone always says boys are the sweetest, but my boy, Keno, was a very assertive male and did not generally get along with other males unless they were super submissive. He tolerated my male galgo, Cruz, well because Cruz was very meek and properly respectful of Keno. And Keno wouldn't hesitate to put what he viewed as a "disrespectful" female in her place either. He growled at my female greyhound, Chloe, once and she continued to make eye contact and lifted her lip. He promptly knocked her to the ground and bit her and she had to have stitches. Right now I have two females. Princess is assertive/bossy and Carly is very submissive. They've only had an issue once in eight years when Carly tried to get Princess to play with her. I intervened and no one was seriously injured. They tolerate each other and Carly respects Princess as the boss.