
To the OP. As an author I think most people miss the complexities of most the characters on your list not to argue with anyone over their opinions but while I don’t agree with all of them I am now motivated to make a more in depth analysis post of these characters. (You forgot Griffith)
I think it would be more acceptable if Light did the killings out of trying to make the world a better place (though it’s still crazy wrong), but he reveals his mental instability and God complex VERY early on. It’s clear that it was never about cleaning the crime, but about securing power and building a world ruled by his judgement
He started seeing the worth of humans after Kimugi worked on him. He was made from hundreds of heartless illegal sellers (MGL?), so he was naturally cruel and heartless. He softened up as he experienced the world and humans. I truly think he would have been a great ruler once his humanity grew large enough. Netero saw that as well. Meruem still needed to judged for his past crimes, though.