Meruem is hands down the best Shonen villain, I do not care what anybody says about this. A person could say Shishio all they want, but that swerve on Meruem is legit. Killua is number one because he's not Gon.Yeah, Gon from a character stand-point does become better as the arcs go on. He was my favourite in Greed Island, however despite his crazy arc in Chimera Ants, Killua rose to my no 1 or no 2 by the end of that arc [tied with Meruem]