I think Stalker is high up the list of best movies ever made.

It is one of those where you go "What am I watching?" when you see it for the first time yet it sticks with you. Then, after a few days, you feel almost a compulsion to watch it again.

I'm not sure how to describe it without sounding all artsy fartsy but the atmosphere itself is a compelling character which draws you in, and how the actors give the most mundane scenes this aura of fantastic mystery.