10. School Days (AKA Nice Boat)
9. Death Note
8. Angel Beats!
One of the few anime series that was not inspired by a manga, Angel Beats! takes place in a quasi-purgatory in which a group of students form the Afterlife Battlefront and fight against God, in this case a small girl named Angel. Complex and sad, yet still outstandingly funny, Angel Beats! examines whether the life you lived previous to dying was rewarding and whether it is possible to find closure in the afterlife.
7. Gurren Lagaan
6. Honey & Clover
Sometimes a show will smash through a wall and break through all preconceived notions of what can be done in a medium. In just six short episodes, FLCL brought all the insanity that it could muster and addressed the issues of loneliness, sex and being adrift in a boring world. It still holds up today and is still held in reverent awe by those who found entry in anime through its run on Adult Swim
4. Paranoia Agent
If you want to delve into a satisfying study of character psychosis, than Paranoia Agent in the right anime for you. It's the study of a city gripped by fear over the random attacks of character named L'il Slugger whose assaults upon the characters may be brutal, but ultimately change their lives for the better. Questions of sanity, repression and anxiety are all hallmarks of the show and the ultimate reveal is an immense pleasure.
3. Puella Magi Madoka Magica
The "magical girl" phenomenon is a bit of a trope in Japan (think Sailor Moon) so many didn't have high expectations of this show when it first debuted. Instead, Puella Magi Madoka Magica turned convention on its head and made one of the darkest and most interesting animes in recent memories. What would you be willing to sacrifice to become a magical candy coated super heroine?
2. Welcome to the NHK
1. Cowboy Bebop
Still the gold standard. It was the anime that made Adult Swim must-watch-TV and was played out almost perfectly in its character arc. For all the humor and action included in Bebop, it was the sense of melancholy that really gave the story poignance. To this day it remains the undisputed king of anime that has crossed the Pacific.