Great idea!

1. Season 6 (lots of excellent episodes, which are among my favorite)
2. Season 7 (also several excellent episodes, but overall the season wasn't quite as strong as 6)
3. Season 5
4. Season 4
5. Season 3
6. Season 2
7. Season 9
8. Season 1
9. Season 8
10. Season 10
11. Season 11 (slipping big time already - no Chin)
12. Season 12 (mostly dreadful, a few ok episodes in there, only McGarrett and Duke remain from the prior seasons!)