I don't care for hair length. Some guys look really good with long 'mop' hair, some look good with short regulation-style haircuts.
However, I don't like guys who have hair so long that it's unkempt and scraggly looking.
I, myself, my hair literally changes with my mood. I have had it super short and I've had it long and scruffy looking. I don't particularly like it super long as I was forced to keep the length all the way past my buttocks by my father when I was a child. He forbid me to ever cut it, yet I was the one responsible for taking care of it, not him. I finally told him unless he started taking care of this mess on my head for me he had no say in what length my hair should be. That same day my mother took me to the salon against my father's wishes and I was allowed have it cut to the middle of my back, that was it. A total of 10 inches were cut and my dad still has those 10 inches of my hair stowed away somewhere. If I find it, I plan to throw it out with or without his knowledge. That's just gross and creepy to have a wad of human hair like that to me.