My top 10 in no particular order:
Cowboy Bebop
Steins;Gate
Tengen Toppa Gurren Lagann
One Piece
Gintama
Code Geass
Death Note
Fullmetal Alchemist Brotherhood
Angel Beats
Fate/Zero
Currently watching and possible top 10 contenders:
Monster
Nodame Cantabile
Kara no Kyoukai
Clannad
Honorable mentions:
Bakuman
School Rumble
Eureka Seven
Samurai Champloo
Full Metal Panic
Disappearance of Haruhi Suzumiya
Summer Wars
Gundam 00
Shingeki no Kyojin
Dragon Ball