I personally like my hair best around bra strap length. My boyfriend on the other hand has no real preference. I went shoulder length short one time and he really liked it. He'd be fine with me doing that again but I like my length better. More stuff to do with it and I can easily slap it in a ponytail or bun to get it out of the way. I can't really grow my hair much longer than bra strap though since it's not thick.
On other people, like what's already been said, it depends on the person. Some women look awesome in short shaved hair, others in long hair. Depends on the face and the personality.