Fight Club. It wasn’t fun to read it felt like the author was ploying with me trying purposefully to confuse me to a point where it forced me to become disinterested. However with the movie i was captivated every second. The book’s attempt to obscure and mystify the reader might have been an intentional stylistic choice, but for me, it didn’t translate well.
Children of Men. The book, by PD James is just not nearly as good as the movie. It has the same premise but, I would say, a different vibe and a focus on religion that really isn’t in the movie. The ending is also completely different. Charon took a great concept with meh execution and really made it sing on film.