1. The Dark Knight
2. Slumdog Millionaire
3. WALL-E
4. Tropic Thunder
5. Funny Games
6. The Bank Job
7. Lakeview Terrace
8. The Ruins
9. Redbelt
10. Death Race
Not that he's expected to only like horror movies, but for the record, it's worth noting that King chose Funny Games and The Ruins as his only two horror picks. His top four are solid, and I'd agree, for the most part (although I haven't seen Slumdog Millionaire yet). From there it gets... kind of... quirky...?
Anyway, if you'd like to read the author's own explanations for his choices, check it out on EW.com.