Short hair is sexy. Long
Short hair is sexy. Long hair may look nice, but when it comes down to the act itself, long hair isn't always very practical. It just gets in the way: "Ow! You're lying on my hair! OWW!"
Plus, with long hair comes the increased risk that she spends a lot of time on her hair. Which means she will want to talk about her hair. And you don't want to listen to that.
Short hair is good. Preferably just long enough to be able to give it a good yank.