Most disturbing ones for me and the ones which have led me to leaving the light on all night, have to be...
As a kid - Wizard of Oz
As a teen - Fatal Attraction
As an adult - Blair Witch
The frightening ones are totally different to me. There are many films which have scared the wotsits out of me like The Exorcist, The Omen, Amitaville Horror and the old Hammer House films etc but 'psychologically disturbing' stays with you.
I've got to say, I avoid horror films as I'm just a complete wimp, but then I always find what you don't see and is left to the imagination is often a lot worse and stays with you longer.