I don't quite get the love for Texas Chainsaw Massacre, but then I only saw it for the first time a few years ago. I suppose much of it's impact has been diluted by time.
For me, the movies I have watched, or would watch, more than once include -- well, I started a list, but most of them have already been mentioned, so I'll mention some that I didn't notice above:
Vampyr (1932; one of oddest movies I've ever seen)
Bride of Frankenstein
The Invisible Man
The Black Cat
The Leopard Man
The 7th Victim
The Body Snatcher
Dead of Night
Them
The Invasion of the Body Snatchers
Psycho
The Birds
Black Sunday (1960)
Kill, Baby ... Kill (terrible title, good movie)
The Night of the Living Dead
Lisa and the Devil
Halloween
Phantasm
Along with these, some movies -- The Bird with the Crystal Plumage, Deep Red, and the truly weird Your Desire is a Locked Room and Only I Have the Key, come to mind -- that, like one Toby mentioned, Zodiac, have a horror-like kick to them but sit on the borderline between horror and the mystery/crime movie. I suppose The Silence of the Lambs applies, as well. Also, glad to see someone mention Suspiria. Watched it again a couple of weeks ago and it holds up.
Among more recent movies, I agree with others about It Follows and The Babadook. And I found Midsommar, Last Night in Soho and X effective. A bit off the beaten path, The Vast of Night works as creepy s.f.