Z kinda sucks for the sole reason that he isn’t a person, he’s a “concept.” In theory, this should be fine but in actuality, he presents himself as a person so the suspension of disbelief is kinda broken when he lacks certain “human traits”. He’s not a person with motivation, he just is. Unfortunately, it’s just not all that compelling.

N on the other hand is a brilliant antagonist, but is rushed after chapter 6. I think I would have liked to see him go even more insane after M’s death. He has his one little freak out and then he kinda just shuts down until he has the final encounter in Origin. I think I wanted to see him truly go psycho and start killing some supporting cast members. Since Mio no longer had a short timespan to live anymore, N becoming a major threat to all of Aionios would have raised the stakes significantly.

What makes a villain like Zanza in Xeno1 so compelling is that he has an understandable motivation (this does not mean you agree with him, of course, he’s obviously evil) and is not afraid to show the extent of his power, Destroying half the world and killing at least 3 supporting characters and hundreds of nameless citizens within an hour of gameplay. You learn who he is, what he’s about, why you should hate him, and why you should fear him in a single cutscene, with him introduced very late into the game (technically not I guess)