The only possible number one(for me anyways) is Gatts from Berserk.
Following him:
Karou from Ai Yori Aoshi (to resist all those girls that want him....he must be a badass).
All joking aside:
Alucard from Hellsing
Walter(the butler) from Hellsing
Mamoru Takamura from Hajime No Ippo
There are plenty more, but i cant possibly fit them all into one message board service
