If this were books versus movies, it would be books easily, for a lot of the reasons mentioned here. Usually the book is the original and much deeper, where as the movie is the adaptation and cuts out a lot of details. Also, with books, my imagination runs wild, characters, locations, scenery and so on.
The thing with manga is though.. I just don't like the comic style. It's always so...busy, and it takes away from my imagination. Anime has the animation to make up for that. So.. Books > movies and anime > manga
