Well,I can't choose between those 3:
Elfen Lied
Shakugan no Shana
The melancholy of haruhi suzumiya.
I don't really like much naruto or one piece,I prefer the original manga versions.
Less Obvious: Magical Shopping Arcade Obenobashi. I loved that show, it was one of the first pieces of "crazy japanese cartoons" that I had the great pleasure of watching, over and over again.
Death Note's plot is starting to get tense, it's soooo good!!! I'm going to download the whole series later. But wow! It's soo awesome, there are 37 episodes. I won't say anything about it though.