I have a 4yr old male yorkie and a 2yr old female maltese, and they get along absolutely wonderful. My yorkie is very loving and sweet! So is my female though
The female is the barker in our house, and our male is the extremely docile one.
I think it's more about the individual dog's personality. What I always say is don't look for a "boy" or "girl", look for the one that steals your heart
and make sure he/she fits in and gets along with your baby.