I like having long hair, but no longer than shoulder length as long as the haircut has been refined rather than just left to grow.
As for girl preferences, long hair girls until they're somewhat matured in which shorter hair would be my preference. Short being possibly up to shoulder length only.
Sure is Sam. For a girl/woman yes, but for a guy it's quite long even if hair length extends past the chin. Sometimes you have girls with hair length twice the length of their head to neck, which I would consider long.
Shoulder length for a guy: Long.
Shoulder length for a girl: Medium I suppose if that's an option. Otherwise, short Saiko. =]