This… is a hard question. I’ve seen so many anime, especially over the past ten years or so, that it’s hard to narrow this down to just one answer.
But after a bit of deliberation, I’m actually going to choose your name. This may be one of the more recent anime I’ve seen, but after seeing it five times over the course of a year (once in a movie theater last April and four times since getting the Blu-ray), I find the work to be just as wonderful as the first time I saw it. The visuals are lush and enjoyable to look at, the music never gets old, and the story and characters remain compelling with each successive viewing. Even though I already know what’s going to happen in the film, I still get caught up in the experience each time I watch it.