It's always hard to sum up the best thing I've seen in the past year. Honestly, I don't remember that much. A lot was good, some were great, but nothing really stuck in the head. Still, the best thing I saw last year was actually released in 2003; the 6 hour long The Best of Youth. This is an astounding film chronicling the life of two Carati brothers, as it follows them from their carefree youth in the 60s to the new millennium. There's a 2-disc DVD available and prepare to be moved.
As I'm an animation nut, a lot of the stuff that I enjoyed last year was animation. I was glad to see Paprika get a release at Cathay, and judging from subsequent anime screenings, it might herald that we'll be seeing more anime in theaters. I also really liked The Girl Who Leapt Through Time, which doesn't try to do too much with its time-travel core. Other stuff I liked was Alexandra Petrov's mini-epic My Love, with its stunning imagery and animation. The promo is up on youtube. (Note that the music in the background isn't from the film, thankfully)
I also enjoyed Lust, Caution, which totally pulled one into the story. Also making the cut is the stunningly imaginative Pan's Labyrinth and Fincher's serial killer biopic Zodiac. So for commercial releases my top 5:
1. Lust, Caution
4. Pan's Labyrinth
5. The Girl Who Leapt Through Time