New 52 - a solid one. Or a zero. Perhaps negative infinity? The lowest, most demeaning rating that can possibly be given sounds about right for the atrocity that is Suicide Squad / New 52 (in general) Harley Quinn.
Pre-Flashpoint - ranging from an 8 to a 10. I love the jester outfit to death and I think it should be her main costume. But it didn't make her look extremely attractive, per se. But that was what was great about it, she was attractive enough but not pandering. Plainclothes Harley was always attractive though, especially when artists incorporated aspects from her jester outfit into her normal clothes.
I voted one because this poll appears to be asking about New 52 and because negative infinity isn't an option on this poll.