2. Twenty Four Eyes (1954) - I distinctly remember every scene in this one, not because I watched it recently, but because when I did, it shook me to my core. It was part of the lineup for JFF, and it was a long movie, a bit on the slower side as well, but I couldn't take my eyes off the screen.
The emotional weight you're left with after you watch the movie is something else, you basically watch a teacher and her students go through life, during a horrific period of time, and before you know it, you've basically watched twelve children loose the spark of innocence and their childhood in the blink of an eye, and you've watched it all through the eyes of someone who literally watched them grow up.
It's just way too realistic and emotional to be watched more than once, but I'm glad I did.