The gory horror movies really don't do anything for me. I enjoy suspensful movies such as the Alien franchise. The scariest things, to me, are the things that aren't really supposed to be horrifying.
Actually, the most terrifying thing I ever saw in movies or on TV was a cartoon I saw when I was a kid. Yes, I mean it. I think I've actually mentioned it here on this forum sometime in the last couple of years.
Anyway, it was a Woody Woodpecker cartoon. Woody was up against a tree surgeon. The tree surgeon was annoyed with all the damage Woody was doing to his trees, so the two of them battled in the usual manner. It proceeded normally until the end. Woody managed to inject the doctor with one of the syringes the doc had been using on the trees. To his horror, the tree doctor sprouted roots, branches and leaves. Frozen in place, helpless to defend himself, he screamed in terror as Woody landed on his nose, aimed his beak at the tree surgeon's eyeball, laughed, and started to attack.
I was traumatized. This stupid cartoon scene scared me more than any other visual image over the years. I felt that tree surgeon's fear deep in my bones. I had nightmares about it.
I guess that I spent so much of my childhood scared out of my mind that most fake horror just didn't matter to me. One notable exception might be the end of Phantasm. ("Boy!") I could relate to that part.
Otherwise, many of them just seemed lame. It seems to me that once someone encounters real monsters, they're just not frightened of imitations anymore. I'm sure that the vast majority of the population feels differently than I do, but I just can't get into most horror movies. I'll find something else to do.