I would prefer books to movies as imagination is more powerful than a movie.

When you read the Harry Potter books, you can picture the characters looking and behaving in the exact way that makes the most sense to you. However, in the movies, the directors and actors force their interpretations onto you. For instance, the movies’ assumption that Hermione was white was not implicit in the book. This became clear when black actress Noma Dumezweni was cast for the West End production of the play Harry Potter and the Cursed Child. Not to mention that in the movies, Dumbledore was played by two actors, Richard Harris and Michael Gambon, which can disturb the image one may have had of the Dumbledore they imagined from the books.