Here's a challenge: come up with a movie that was better than the book upon which it was based.
I can think one right off the top of my head, and it's an extreme example: Who Framed Roger Rabbit?
The book, Who Censored Roger Rabbit, is justifiably forgotten, one of those "parodies" that relies on a poorly-concieved gimmick for its "humor".* The movie, however, is an all-time classic.
*You know the type.
"Let's do a Star Trek spoof where all the characters are furries!"
"Okay, got any good jokes in mind?"
"Dude, they're furries!!!"