Something that suits you and you're comfortable in. I hate it when girls try to be something, it's so easy to tell. Just wear what you naturally gravitate to. If you like it and feel comfortable and confident in it than you'll be really attractive. Confidence is key. Now, if you're comfortable in baggy sweaters etc...that's cool but not the sexiest thing alive. I love a girl that can pull off a sexy or cute outfit with confidence. I am especially partial to a girl who is confident enough to go braless, something about that says a lot about a woman to me. Doesn't have to be slutty, can be in a cute/reserved dress or whatever. I am a boob man though.