I put this in Lifestyles since I think the choice is often dictated by lifestyle.
I used to have long hair (only made it to shoulder-length before giving it the axe). I actually grew it out while working my current job over about 15-18 months, and didn't get too much shit about it since I work in a fairly casual office setting. I decided I didn't look my best with it (it's very fine and straight, so it gets limp easily).
I actually got upset at myself for feeling like a girl, toying with my hair every time I passed a mirror. It also simply doesn't give the best first impression, and when you're a young professional that's a strike against you that you don't need.
Sometimes, though, I wish I was still the guy in the photos.
I think it's dicktated by something else.