Is far and away, Toy Story. There's a Toy Story 3 coming out, and my kids are blase about this fact. Too old to think it's cool, and this worries me. How can you lose a love for Woody and Buzz??? They are classic.
Toy Story was the first movie I took my son Trey to see. He was 14 months. His baby brother stayed with my mother and apparently, cried the entire time we were gone. But Trey...he was mesmerized for the entire time. He loved Woody and that's his personality. He always went for the basic toys: the Thomas the Tank Engine, the Legos -- whereas Jonah liked Buzz and all the electronic, spinning, loud toys like video games and toy guns with lasers.
I love that I have my own Woody and Buzz and I'm truly bummed that they won't go with me today to see Toy Story I & II in 3D. But that's what their younger siblings are for.