Character-wise, which do you prefer?
I think Nishi's weaknesses, youth, history, you know, everything...just make him a more fleshed out character despite his smaller screen time. You see his humanity in the Tanaki mission.
Izumi on the other hand seems to be a 2D "I AM SUPER EVIL AND STRONG LOL I AM GANTZ VEGETA" character, without the compelling elements of Nishi's sort of apathetic social darwinist character.


Also, I don't get the deal about people making fun of him crying...I mean, he's a middle school kid who just got his eyes and eardrums blown up, is dying a horrible painful death in total agony, and was ten points away from 100...Yeah, he's crying. Maybe a 2D character like Izumi wouldn't because he's "LOL IM A HARDCORE EVIL VILLAINZ DUDEDDD", but give me a break...of course Nishi would cry for his mother...anyone would.