For myself, as a little girl I always enjoyed friendships with boys more. I was a tomboy, who liked to play with cars and climb trees, and other girls didn't like to do that. Plus, I always found girls to be high maintenance and whinge about things, while boys just got things sorted.
This was me too. I was definitely a tomboy. This may date me slightly, but when I was in elementary school we would always play "Star Wars" at recess and since I was the only girl playing with the boys they wanted me to be Princess Leia so they could "rescue" me. It would make me so mad because I was much more suited to being Han Solo or even Luke, so I would cave to being Leia every once in a while if they agreed I could be Han or Luke the next day. All through my life I've always had more guy friends than girl friends, which has led to some awkward situations like when your high school or college buddy starts hitting on you or asks you out and you completely view him as a brother-figure.
Both my girls have friends that are boys and I encourage them to play with the boys. When they come home from school and tell me about all the drama going on with the girls that is the first thing I tell them - go play with the boys! DD10 probably plays with the boys more just because she doesn't have much interest in the "girly" things the girls are doing and some of the girls in her class are not very nice. DD8 is very social and has lots of girl friends, but the girls in her class are over the top drama for such a young age. There is just something about the dynamics of her age group that creates constant turmoil amongst the girls (maybe too many chiefs or however that saying goes). The teachers and school counselor have even mentioned how much drama there is with the girls in DD8's class.
I hope they both continue to have friend type relationships with the boys. I view having friends of the opposite sex as very beneficial in life - based on my life experiences.
