In no particular order:
Nico Robin(One Piece) - Just because in a way I can relate to her.
Suzuki Sonoko(Detective Conan) - It started as a joke though because nobody liked her. I think she is annoying and stupid but then I started to kind of admire her for being such a nice friend to Ran. Something I can never do. :V
Niizuma Eiji(Bakuman) - SPIN!! Manga genius. He's definitely the main antagonist but he is not evil, not the usual shonen manga antagonist. He is actually the less serious, more fun version of L from Death Note.
Ryuk(Death Note) - He was neither good nor evil, he was just bored so he entertained himself. He was neutral for his personal gain.
Donquixote Doflamingo(One Piece) - The bastard. I can't just hate him, not after his speech about Justice. He definitely knows how to play the game unlike some guy named Crocodile.
Hisashi Mitsui(Slam Dunk) - He's got a nice backstory. It's a shame the Manga already ended with little exploration to the characters. But then again, Slam Dunk is about basketball and I guess the ending was just a perfect final touch to the reality portrayed throughout the series.
Hisoka(Hunter X Hunter) - I don't know. I like twisted characters.
Hiramaru Kazuya-Yoshida Koji Combi(Bakuman) - Got a good laugh out of their hilarious interactions.
Zaraki Kenpachi(Bleach) - I don't know everything about him but after watching 40 something episodes of Bleach, I find him the most interesting character.
Bartolomeo(One Piece) - More like BarTROLLomeo, weird and adorable character, I just love him.
L(Death Note) - Cool character. The sole definition of Justice, or at least the Justice that most people accept today. He is definitely more experienced than Shinichi as a detective because you know, L hid his identity while Shinichi was just...reckless and too hasty to solve a case and then he shrunk.
Light Yagami(Death Note) - A representation that no matter how smart a teenager is, they still make bad judgment or is it? Ahh! The morality of his justice. I just can't help but think about it.