Eh, i liked nero. There's only so much leeway with her character after all. The later stuff in her my room moments is fairly good though. Her interactions with tamamo when they are on the same side are also fairly interesting.
Frankly, i liked elizabeth as well till she went full edge. She was pretty cute in tamamo's campaign up until the point where she was corrupted. Annoying the all of 1 time she showed up in nero's first one, but cute in tamamo's.
On the subject of karna though, i really liked his character in extella. In GO, i just thought he was some edgy overdesigned shit, but extella did wonders to make me reverse that stance.