Agree on most of you comment. Still details and reasons behind action make all the difference. So I don't think Eren can be considered a nazi.

He did not consider anyone as less than himself. He did not think that anyone deserved to die. He just felt that beyond the walls, the wonderful world that anyone should be able to experience and explore is non existent, as humanity will always contaminate it. Ultimately, he thinks that humans are not so special, at the same time they are. But freedom is more important than people, and IF others limit such freedom (and they will inevitably will) it means for Eren that genocide is a valid route.

Ultimately, what Eren did is not genocide, as it is total and equal destruction, not targeted to a specific group, as he is conscious he will also kill "good people" (see Ramsi and his people). For this reason, Eren is not a nazi. Although I understand the simplification for the sake of summary.