My ds, 4.5, had long hair until recently, when he requested a cut so he could "look like Bruce Wayne". I gave him a bowl cut.
I liked it beforehand because his hair was lovely and soft, and I like the look of long hair on most people. I like it now because it's easier to keep untangled. In the big picture, though, I don't much care either way. It's HIS hair, ykwim?
I think it's funny/fascinating how big this issue is to a lot of people. My next door neighbor is clearly enormously relieved that he has a "boy" cut now. Eek! Gender confusion! The worst of all worlds!

Although I will say that I find the close-cropped, military-type haircut I see on MOST boys around here very unattractive. It's such a severe style; I think it only compliments a face with sharp, angular lines. Which isn't too common in a healthy young child.