Prisoner of azkaban book and movie: For christ sake lupins a hot guy covered in scars who ends up being a werewolf and his best friend is a super nice guy who turns to a dog and then they had to save buck beak and HERMIONE punched malfoy! AND snape buts in all swift like *swoosh* Exspelioarmus! #cool hair flip....
Hbp is best book because U get to see harry really working with dumbledore to take down voldy. Also you want to know what devious thing Draco is doing. And Harry's character arc through this book was incredible.