I generally like shorter hair, ponytails, and not overly curly. However, hair is one of those things that can vary from person to person or moment to moment. Some people look good with short hair while others with long hair. At the same time a single person can look good with short or long hair. This applies to styles as well as length. This applies to others, not just me.
For me though, hair style is probably one of the least important issues when I'm looking for someone. But, if a person is wearing a style that doesn't fit her well it would hurt things some. But since hair is so easily changed it isn't like it's something that weighs all the much.
I'm not into curly or beads or died for the most part unless it's a natural color like blonde, brunette, or redhead, but don't go with too extreme with the blonde or the red or it will look obviously unnatural. I don't really like pigtails either.
Everything else usually looks goods in my book. Girls with medium length hair also look good in pony tails and buns. Short hair looks good on a lot of girls I know. Straight always looks good and wavy is iffy depending on if it fits that persons style.