I'm really surprised that I'm the only one who's voted GoF. I hated PoA for the longest time, and after a few rereads as an older reader, I like it, but I've always loved GoF. It's the middle book, the transition. I think it marks the point where Harry learns he really has to come to terms with the world, because Voldemort's back. It's also the first time Ron's loyalty to Harry is really tested, and it's so sweet.
"My pet, I've been to the devil, and he's a very dull fellow. I won't go there again, even for you..."
"Harry Potter is about confronting fears, finding inner strength and doing what is right in the face of adversity. Twilight is about how important it is to have a boyfriend." -Stephen King
Space: the final frontier. These are the voyages of the starship Enterprise. Its five-year mission: to explore strange new worlds, to seek out new life and new civilizations, to boldly go where no man has gone before. — Captain James T. Kirk