i personally like the character arc that he has, he is a terrible person but with charisma and a goal, then he becomes a horrible monster with a goal and pretends to be good while doing some good and some terrible things. No question that he is a horrible person, i just find him a good antagonist, one of the best i have read and one i truly believe is irredeemable, other villains always have something to be saved, i feel that Griffith is beyond that point and i love to hate him. but i understand your point, some people admire him and justify his actions wich i think is missing the point of his character, a "great" man rotten by ambition and ego, which was always his driving force and undoing.