This is the list. These are the classics. These are my favorites.
Cowboy Bebop - bounty hunters of the future. comedy and drama as well as action. Great soundtrack. Trigun - comedic dystopian world and one heck of a protagonist. Haibane Renmei - somewhat dramatic but paints a vivid possible afterlife. Excel Saga - insane sci-fi comedy centering around some truly messed up characters. Now and Then, Here and There - very thick dramatics in a dystopian parallel world. Ghost in the Shell - future sci-fi centering on a cyborg protagonist. Oban, Star-Racers - futuristic ship racing to win the ultimate prize. Azumanga Daioh - quite a funny bunch of quirky schoolgirls. Aeon Flux - a future assassin gets killed repeatedly and a story develops from there. Di Gi Charat - lighthearted and messed-up alien antics of a game store mascot. Hare Nochi Guu - omg what is Guu exactly? that's what Hare would like to know. Rurouni Kenshin - often funny but action-oriented tale of a samurai who gave up killing. IRIA - Zeiram the Animation - future bounty hunter encounters unkillable monster. Evangelion - organic mecha pilots face the ongoing threat of alien 'angels' in Tokyo-3. Millenium Actress - the story of the life of an actress chasing a lost love. Metropolis - future politicial robot film by none other than the creator of Astro Boy, Osamu Tezuka. Battle Angel - adaptation of the GUNNM manga, which I would suggest reading. Kino's Journey: the Beautiful World - occasionally philosophical journey of a girl and her talking motorcycle.
That's it for now. I will expand this further, gradually.