I have 2 male dogs (not yorkies) who are best friends. I had Ziggy (80lb Australian Shep mix) first and when he was 1 1/2 years old we added Oliver (12 lb shih tzu). They play together constently and have never, ever fought. I added Belle (5lb yorkie) to the family in Feb and she is the one who starts fights with Ollie - so I think that it's the individual dog's personality more than the gender. Good luck in your decision.
