Anyone who says Prisoner of Azkaban isn't the best book (and tbh, film) is lying.
I friggin' hated HBP, and some parts of Deathly Hallows, although have just got back from Pt. 2 and loved it!
I know the dark stuff is all 'epic' and what have you, but there was a certain charm about the first three books that wasn't replicated when Voldy came back.