@Apunkin- I think that's a very individual decision, one that should be decided based on his maturity level, the sort of people he hangs out with, and what the hairstyle he wants says about the youth in your community.
Like you, I prefer short hair cuts, but my son, now seventeen, likes his hair long and straight. Sometimes he puts it in a pony tail, which I can’t stand. I let him decide for himself from the beginning, but that was worked for us. Your son might need more guidance.