Azumanga Daoih.
The show is hilarious, the characters are well-conceived and real, in their odd little ways. It makes me laugh my ass off with its wonderful weirdness and can move me to tears at times with its sweetness (while never being twee). The art style is clean, with random sojourns into surrealism. All in all, a great little commentary on life and all its wonders and weirdness. And it has it all: Action! Car chases! Drama! Romance! Adventure! Suspense! Horror! (which is maybe why it was so popular to use in amv's for a while---you can make whatever scenario you want with the thing).
That, and I love, love, LOVE Osaka. Just looking at her makes me happy. In fact, I love Osaka this much:
