DeathNote is the only one I've really enjoyed but my sister got me into Naruto for a while before I realised its shit.
Hellsing Ultimate (one of the few where I think the dub is better than the subs) Elfen Lied (dark anime with a good storyline) Hunter x Hunter (made by the guy who made yuyu hakusho and has many of the same elements. It's a bit more of a kids anime, but it still has mature parts especially later in the series) Yakitate Japan (it's a comedy anime about baking bread, if you liked iron chef you will probably like this. Despite its rushed ending it's one of my favorites)
Code Geass, Hetalia, Fullmetal Alchemist, and Cowboy Bebop but i used to watch Pokémon, Yu-Gi-Oh, Bleach, and Naruto when I was younger.
I have to say Afro Samurai! I liked the first season better then the movie though and Samuel L Jackson is always a plus.