"Total Recall" - the 1980 one , loosely based on the Phillip K Dick sci-fi short story. I enjoyed the movie way more than the short story.
The 1979 "Salem's Lot" - wouldn't say it's better than the book , it made some changes from the book but the changes were very effective - the silent barlow vampire was way scarier on screen than what it was described in the novel .
I found John Carpenter "Vampire$" to be better than the Steakley novel which i had read ages before the movie.
Don't quite agree with the bleak and ironic dark humor ending of "The Mist" but i loved the movie almost as much as the novella. In the novel , you only have your imagination to go with the words but in the movie , it got whatever nightmarish creatures written in the novel down with the visuals so it's great.
Loved "Fluke" as a movie just as much as i loved the James Herbert novel.