I has watched only about 60 anime series, but here's my recommendation.
1. Tengen toppa gurren lagann. (WHO DO YOU THINK I AM?!)
2. Code Geass (Death note with Mechas)
3. Higurashi no naku koro ni (One of the biggest mindfucks in history.)
4. Higurashi no naku koro ni kai (sequel to the higurashi naku koro ni, but answers the major problems.)
5. Seto no hanayome (The first few eps aren't very funny, but it gets very funny after ep 4. If you think the last ep of Gurren lagann was epic, then watch the last ep of this.)
6. School rumble (Funny romance comedy. Not as funny as seto no hanayome, but still has its own charms.)
7.Kino no tabi (Great series. I have the first 9 books in Korean. It's based off a light novel.)
8. Gundam 00 (The newest, but I shed manly tears in ep 23. It's the first Gundam to have HD, and the first to have a non-fictional background.)
9. Azumanga daioh (It does everything Lucky Star didn't do)
10. Seirei no moribito (The one of the most budgeted anime of 2007. Made by the company that made ghost in the shell)
11. Sola (The script writer is the writer of Air, Canon, and Clannad.)
12. Fullmetal alchemist (The anime that convinced me that anime wasn't full of Naruto, Inuyasha, and Bleach. It WAS the first anime I liked in 4 years.)
13. Death note ( The first ep just starts off with the background and all, but the second ep blew me away. Don't watch the dubs. You'll thank me.)
14. Sayonara zetsoubo sensei (I spelled it wrong, but anyways, it's really funny. )
15. Cromartie High (Incredibly short, but incredibly funny. It also has Freddy mercury in it, so WATCH IT!)
P.S I prefer not to watch mainstream shounen series, since they usually end up SUCKING. Fullmetal and Death note were the exceptions.