Hmm.. That is a really tough question to answer. There are so many, but these are the ones that come to mind, right off the bat.
The Hand That Rocks The Cradle - I absolutely love this movie. I wasn't even ten yet, and I was totally enraptured by the psychoticness that is Ms. De Mornay.
Se7en - I didn't see this movie until a few years after its release.. No wonder I wasn't allowed to watch it!! The MO was played out in a manner that you would be scared to ever sin ever again. LOL
The Number 23 - I know that a lot of people didnt think that Jim Carrey could do well in a serious role, but I think he was awesome in this movie. The story itself, albeit sometimes dragging a bit, made for very interesting conversation afterwards. And sadly, it it true. Everything does add up to 23. (Trust me, I spent nearly 4 hours after this movie adding random things up)
Ferris Bueller's Day Off - I don't know, don't ask. I love 80s movies, and this has to be one of the top picks. No matter what is on television, or if i'm busy doing something, if this is on, I will stop whatever i'm doing to watch it. It's just that good. RIP John Hughes
American Beauty - Okies, I know that most people would say that this is just a messed up movie (at least that's what my ppl tell me

) but words cannot describe how wonderfully it it played out. This is truest sense of psychological drama.