I think its simply down to what suits the girl best. Some girls look fantastic with short hsir. On the whole tboigh I think you are right, guys like long hair. Maybe its because we seem to be programmed these dsys that girls have long hair and guys dont. Thereby guys think long hair is feminine and short hair more masculine. What constitutes long hair? Id say shoulder length and beyond.
Guys like good-looking, well styled hair, and it's easier to get that look if it's long. I like short hairstyles too, but well styled long hair looks more glamorous and attractive than well styled short hair to me.
The cutoff for "long" hair is about an inch past the shoulder.
Longer hair is almost always better. I'm sure there can be difficulty in managing it, but mid-back length hair is extremely sexy. I've literally gotten my hair cut shorter just to get my wife to grow hers out long.