Least favorite book(s): Order of the Phoenix and The Half-Blood Prince. Reason, the fifth book dragged a bit until it reached the end, where it picked up the pace. Would have liked the pace to be moderate. The sixth book wasn't bad, but it felt weird between the 5th and 7th books which were pretty dark.
Least favorite movie: Harry Potter and the Prisoner of Azkaban. Reason, it was too short, and most of Ron's lines from the book went to Hermione in the movie.
Favorite book(s): I liked the first book for starting the entire franchise, and I like the seventh book for bringing the franchise to a close. Also, as a Ron fan, it portrayed him the best in each book listed, even though I wanted to punch him for abandoning Harry and Hermione for a short time in the 7th one.
Favorite movies: Don't have a particular favorite.