My favorite Stephen King book, and filmed adaption, is THE STAND. I don't often reread novels, but THE STAND was an exception. And the TV miniseries was everything I wanted it to be.
Second favorite would be a tie between THE DEAD ZONE and IT. I really liked the film version of THE DEAD ZONE, but the TV adaptation of IT should never have shown us IT. A big disappointment, they should have showed the adults seeing IT, but left it to the viewers imagination.
Come to think of IT, I reread both THE DEAD ZONE and IT.