I have decided to use my memory to answer this and not the Internet -- my memory can't be trusted with where my keys and wallet are, so it may fail me here as well. But if memory is supposed to keep track of what things mean and how much, then mine says go with "Adaptation" from 2002. I remember sitting in the dark being both moved and jealous of what Charlie Kaufman and Spike Jonze accomplished -- I wanted to give up writing because it seemed like they had taken everything I had ever wanted to say and said it better, funnier and faster.
I left the theater knowing I was doomed to spend the rest of my life imitating them and knowing it. And yet what they were saying and doing was so inspiring that it was impossible to quit. They didn't just change the way I thought about how I do my job, they reminded me of why I wanted to do that job in the first place. There is a moment in the swamp at the end where Charlie and Donald are having a conversation and Donald says, "You are what you love, not what loves you." That may look meager here in type, but it could have saved me and everyone I know a great deal of pain. My memory just reminded me of how much I liked "Pan's Labyrinth" and some other movies ... but I need to go find my wallet now.