Okay guys which is more attractive on a girl, long hair? or short hair?

I have long hair and I always get compliments from it. Recently I decided I want to cut it like REALLY short but my mom doesn't like that idea at all. She told me a quote from something like "A girl's hair is her glory" and that guys like girls with long hair better. So I thought I'd ask some real guys what they think. So which is more attractive? Long hair or short hair on a girl?