I think HxH and I don't give a fuck if one piece angels cry about it. HxH's characters getting development feels more natural and realistic.
OP characters and their development feels very expected and foretold by everyone, there is no naturality in this.
Prime example would be Gon and you Light probably know that I never liked MCs and especially Gon. His emotions thru the Chimera Ant arc feel so fucking realistic and progressive for someone of his age/kind and etc....
Luffy would try to liberate Pitou and give him a spot in the Grand Fleet.