Favorite anime

Okea all! Go here to write one favorite anime (one) and why you like it)
For example (I'll start):
Hunter×Hunter
It is interesting to observe a plot, unexpected twists, diversity, rapid development and a lot of events, as well as interesting and unusual characters, their behavior.
And the opening themes are good, and, in General, the anime leaves a good mood after watching, not counting a really tough series.