The Godfather films (especially parts 1 & 2) are some of the most beloved movies of all time. You can include me in that category. But I actually read the book first, and it's an excellent read!
I'm glad that The Wild Robot movie has gotten rave reviews, but the book was even better! I hope people will read the book series. (And you get to find out what happens to Roz after the end of the movie.)
To Kill a Mockingbird is a classic, both the book and movie. This is a hard one to call. I love the story in each of its forms, and it's almost a tie for me. I give the slight edge to the book, but ask me on another day, and I might give you another ...
There are so many details in the books that couldn't make it into the Peter Jackson movies. But even so, the beauty and power of the films give them a slight edge for me. (Controversial opinion among devoted Tolkien fans, I know.)
While the book was fun, the movie was iconic. What? Like it's hard?
I first read The Great Gatsby in high school. The 1974 film version was well-cast, but the 2013 film captured the wild, hedonistic 1920's of the setting.
Jurassic Park is one of those stories that I loved both the book and movie nearly equally, just in separate ways. If you haven't read Crichton's books, this is a great one to start with.