I think "Rosemary's Baby would give "The Exorcist" a run for it's money.
There's no cheap "Bugga Bugga" moments like the slasher in a mask movies just a general feeling of evil waiting til the big moment her baby is revealed in all it's horror.
I like "The Omen" as well.
These movies plus "The Birds" and "Psycho" hold up really well over the years while the Jason and Michael Myers movies look trite with the "gotcha" scenes replacing the tension of a well written script that Alfred Hitchcock did so well for so long.
For kitsch, I really like The Fearless Vampire Hunters"
Sharon Tate was so beautiful.