I have both girls and boys. I prefer girls, I guess because I always grew up with all female dogs. My girls never fight and have wonderful personalities, they are cuddly as can be and playful. That said, they do mark like little boys, so just know getting a girl doesn't guarantee that they won't mark.
Now my mom prefers boys. The boys love her and are very dedicated to her.
I really like both but the girls just gravitate towards me while the boys gravitate towards my mom. Her boys are cuddly and playful just like my girls are cuddly and playful.
There is a saying for yorkies that goes, female yorkies love you while male yorkies are in love with you. I would say that is pretty accurate.