I have only ever had one dog on its own, when I first got married, since then we have always had at least two, we now have three. I have two bitches and a dog, only one bitch speyed (due to a pyometra), and they all get one famously. In fact I have difficulty taking one out of the house on its own, as they refuse to move until 'miss alpha female' is going out too.
I dont believe females are more loving than males, nor are they more intelligent. My eldest is a 4 year old bitch, and is far more boistrous than the other two put together, one is 2 years old and the other 12 months.