Oh man, I'm not gonna lie, Pet Sematary really freaked me out when I first saw it. Not in the sense of something impossible or new, but in the sense of how much the movie can pull you in when you're 4 years old. *<:)Nightmares for quite some time.
I'd go with:
1) Pet Sematary
2) Silver Bullet
3) I guess The Shining, mainly because nothing else comes to mind right now.