it's a tie between Fight Club and The Shining (the Kubrick version, not the made-for-TV-movie). I enjoyed both films more than the books they were based on. the makers of both films used their creative licenses to make something unique and fresh rather than just mindlessly following the source material like so many book-based movies do.
First you will awake in disbelief, then in sadness and grief and when you wake the last time, the forest you've been looking for will turn out to be right in the middle of your chest.
Lord of the Rings was amazing! Even though TreeBeard was an absolute moron (guh, why?!)
The BBC version of Pride and Prejudice rocks my socks off.
Sense and Sensitivity and Persuasion were good too!
Also, the James Bond movies! Rawr!
I also enjoyed several films before reading the book. For instance, I enjoyed Ben Hur, which caused me to read the book. (The book, by the way, is absolutely brilliant, and you should read it. There's a reason why it was only kicked off by "Gone With the Wind" on the bestsellers list after years and years!)
I watched several movies without reading the books. I liked the Bourne trilogy, for example! T'was fun.
Ubi caritas est vera, Deus ibi est.
"The mark of your ignorance is the depth of your belief in injustice and tragedy. What the caterpillar calls the end of the world, the Master calls the butterfly." ~ Richard Bach
Both adaptions of True Grit(1969/2010) were fantastic. Neither was 100% faithful to the written version but thats the challenge I guess. I liked the Rum Diary though I admit I never read the literature.