I'm attracted to guys and girls and I look for different things from both.
In a guy, I like someone who gives me my space and isn't demanding. My personality is an acquired taste so he'd better be a good fit or he's not going to want to be around me for long. Physically I don't really care. I guess I'd like him taller than me. Mentally I'd want someone intelligent, somewhat serious and not a stupid show-off.
In a girl, I like femininity. I'm attracted to quiet, understated girls, hopefully with a creative or artistic side. Physically I like girls to be shorter than me but I don't really care as long as there is some chemistry there.