L is my favorite anime character of all time, so yeah he gets my vote. He has everything, he is unique, charismatic, intelligent, funny and despite his oddness and unrealistic and exaggerated character design, still comes off as a very human character, which is where Near failed.
I also really liked Light... never bothered to think about whether his actions and methods were morally and politically right or wrong, regardless of that, he is still a fascinating character.
Mello is awesome too, ambitious, reckless and hardcore, when he appeared you knew you were gonna get something good. Plus his fashion sense is the best in the show, god those were some awesome coats he had.
Those are my top 3 in the Death Note, but I still like some others... Ryuk is entretaining (which is funny, because all he wanted was to be entretained), Matsuda is mostly comic relief but still manages to make me root for him, plus he has that badass moment in the final episode, and Misa is a good character too, interesting contrast to have a dumb blonde (well she still has her smart moments though) in the middle of those two geniuses.
Biggest disappoint to me was Mikami, awesome when he first showed up, loved his backstory and his "Sakujo" and "Kami!", but in the last couple of episodes he went too psychotic for my taste.