1. Serial Experiments Lain, It's The Second coming of Jesus, I even did a review!!! [http://www.escapistmagazine.com/forums/read/326.214642-Sacmans-Sac-tastic-Anime-Review-Serial-Experiments-Lain]
2. Ergo Proxy, A lot of people say Ergo Proxy is an anime you have to think about but on reflection it feels more like a parody or satire of over pretentious anime like Eva. The last episode is even titled "Deus Ex Machina."
3. Elfen Lied, What this show does is hard to explain. It's gory and bloody and filled with tasteless nudity but I loved it. Elfen Lied just got me so attachedto the characters that come the end I cried...
4. Welcome To The NHK. It's hard to explain... I mean it's really the only slice of life I've ever loved this much but I'm just not exactly sure why. It could be the pitch black humor, the realistic characters, the social satire, or even the brilliant writing. Honestly, however, I think it's more the fact that Sato's, The main character's, situation hit's very close to home for me...
5. FLCL. I hate to sound like everyone else but FLCL is 6 episodes of awesome craziness!!!
6. Blue Sub No. 6. I used to watch this as a kid on Toonami and I really didn't get it but going back to watch all 4 episodes now I can safely say it's one of the most polished OVA series I've ever see, with an amazing soundtrack, great action, great animation, a standout art style, and one of the most coherent messages about human nature I've seen in anime.
7.Gundam The 08TH MS Team. It really stands out for me because it's one of the few Gundam series that give a general sense of fear because the action is unpredictable and the characters really endear themselves to the audiance...
8. Paranoia Agent. It's a truly great murder mystery that keeps you guessing at every turn but look past that and you'll find a very intriguing deconstruction of the human mind...
9.Gungrave. Possibly one of the most underrated shows I've seen. Gungrave is a truly great story about friendship, love and betrayal without ever falling into cheesiness the great animation, spectacular fight scenes and well thought out character development doesn't hurt either.
10.Higurashi No Naku Koro Ni. Despite having no real plot, since I consider Kai and Rei to be non canon, Higurashi is one of the most atmospheric and frightening shows I've ever seen. It constantly keeps you guessing and always gives a feeling of paranoia and dread...