Favourite film is definitely Prisoner of Azkaban. I enjoyed the feel of this movie, as I think this is kind of the turning point before things start getting a lot darker. There's the addition of Sirius and Remus, which also provides people in his life that are not only family that Harry has chosen for himself, but they in fact his family and he would have grown up with them as uncles if his parents had survived. Also Buckbeaks flight is both one of my favourite scenes, and also my favourite song from the soundtrack.