I always thought Hermione would probably fit Ravenclaw best and is the classic example of a Ravenclaw. Sure, she was brave and capable of heroism but so is Luna who's a Ravenclaw. So how come Hermione is in Gryffindor but Luna is in Ravenclaw? More importantly how did Cho Chang end up in Ravenclaw? Personally, I think the series would've been more interesting if Harry was a Slytherin, Ron was a Gryffindor and Hermione was a Ravenclaw but they were all still best friends and the main heroes of the series because true friendship doesn't care what house you're in.