They are my two favorite authors ever!!!
Blade Runner, based on a PKD book, is my favorite film, but I have to go with King in the movie department.
The thing is, with movies based on PKD books, they are "loosely" based on his books for the most part. If you read Do Androids Dream of Electric Sheep and We Can Remember It for You Wholesale, you're going to be in for a pretty different experience then watching Blade Runner and Total Recall. I remember reading that 'Flow My Tears, the Policeman Said' is going to be made into a film and I'm really looking forward to seeing how it's handled (very good book!!!!)
With King, the films (or TV mini-series) follow his books pretty close (besides Kubrick's version of The Shining). Stand By Me was a great adaptation of The Body, the same with The Stand, Shawshank Redemtion, Hearts in Atlantis, The Green Mile, Misery, among many others.
There have only been a couple movies that I really liked based on PKD's work, but with King there have been a ton.