When I moved to Hawaii, the 40 ft Matson container carrying my belongings was supersized. It was needed to carry over 10000 movies, of which 10% were from the horror/science fiction genre. Horror, sci-fi, and action are so over the top nowadays that I doubt it really scares people anymore.
The classic stuff had a tremendous impact on me, when I was a child. Frankenstein (1931) and the Wolf Man (1941) ranked as the top two scary movies.
All I can say about more modern movies like the Saw series, is that they are gross and disgusting. The directors and writers need to spend more time building up the suspense aspects of the story. Do not give up everything in the first 15 minutes. This is why Twin Peaks is a great series- it was binge worthy. I wonder why Hollywood has not made a horror film about 1/6, where the insurrectionists break into the hiding rooms inside the congress, as the audience tries to figure out which mole has a concealed carry weapon cocked and ready to kill their fellow legislators.