Love me some Stephen King, and have even hung out with his son, Joe Hill, a bit.
Favorite stories are numerous: The Boogeyman, Gray Matter, I Am the Doorway, Battleground, The Graveyard Shift, The Body, Rita Hayworth and the Shawshank Redemption
Novels: The Stand, It, Salem's Lot, Thinner
The man has created so many great pieces we sort of take him for granted. Even his worst stuff is better quality than 90% of anyone else's.
I agree on Koontz. I loved his classic stuff like Watchers, Darkfall, Servants of Twilght, etc., but anymore it's just bland drama, with a little quirky and force humor thrown in with some sort of weird aspect. Most of his characters nowadays are very much the same as another. Odd Thomas would probably be the exception, but there were a couple of his books where absolutely nothing happened!