Hermione !!!!

He'd wipe the floor with Hermione. J.K. Rowling herself has said that Harry would have beaten Hermione in a magical duel.

Harry just had luck most of the time...and friends

Ha! He's cunha is right! Hermione is an exceptional duellist, capable of outmatching even Death Eaters, as shown in the battle at the Department of Mysteries, at the Lovegoods' house, and in the Battle of Hogwarts. However, Rowling has stated that while during the first three books Hermione would have beaten Harry in a magical duel, by the fourth book Harry is so good at Defence Against the Dark Arts that he would have defeated Hermione.

^But Hermione is not gonna use any Dark Arts. So whatever spell Hermione uses,that is not Dark Arts, Harry can't defend himself.

Hermione may be smart, but Harry is naturally gifted at using magic to fight. Hermione never would have survived against Voldemort. That said, if Harry wasn't there, I'd say Hermione.