The all-time scariest movie for me, but probably only because I was so young when I first watched it, would be Pet Cemetary.
That movie scared the ever-loving piss out of me, and I refused to watch it again for like 6 years, given that only made me like 14 at the time, I also wouldn't go near black cats.
Movies don't really bother me anymore, though I can't do 'gore' flicks too well these days. I used to be a huge Takashi Miike fan, but somewhere between Visitor Q and Audition I just couldn't do it anymore.
My list for top 5 scary/weird movies goes:
Pet Cemetery
Visitor Q (Which is hilarious but disturbing)
Happiness
Original Last House on the Left
Audition (Seems too...plausible, other than the guy in the bag.)