Initially, my (idea of an) ideal roommate should be a guy (saying that he is "male" doesn't means that he necessary has to be a guy? I know it sounds weird to say just "male", although it wouldn't sound weird just "female"). If sharing a room with a person of the same gender is (already) hard, sharing a room with a person of the opposite gender might/must be even harder. In addition, he should be neither too quiet nor too talkative. As I'm a quiet person, I wouldn't like to live with a person who I would rarely have a conversation with, as well as/ as the same thing would happen with a person/someone who talks too much, specially when I'm not in the mood. Finally, he should not be very spacious. I don't have problems with sharing my stuff, but I like to have my own space guaranteed.