Film Challenge: Watch 12 best films ever made based on a book

So, my brother gave me this challenge as part of my list of resolutions. Obviously, I’m over the moon with this challenge, I can be a couch potato and at the same time feel like I’m achieving one of my goals. So, the problem is that we can’t agree on which films I have to watch.
The genres of the films are as follows:

1. Best Thriller
2. Best Sci-Fi
3. Best Chick Flick – Romantic Comedy
4. Best Horror
5. Best Documentary
6. Best Action
7. Best Adventure
8. Best Drama
9. Best War
10. Best Musical ( seriously?!)
11. Best Gangster
12. Best Animation

Right, let me know what I should watch and I’ll put the popcorn on and find the corkscrew. Finally, I know a lot of you are film buffs so don’t be shy, all suggestions are welcome.