The Princess Bride
I have seen this film over 20 times and I never tire of it. I know the whole script off by heart. And I'm still amazed and pleased at how this film makes me feel. It cheers me up no matter what. I feel the biggest surge of nostalgia watching this film. It was the first film I watched that had a 'meta' theme to it. It was self-referential and brilliantly wicked and clever on what it did.