Honestly I do not use either (very often). I call them American. If they have an issue with that, which is fine if they do, I call them whatever they want to identify themselves as (Navajo, Piute, Sioux, Crow...). In the case of Native Americans I can see the arguement being made for the term and could accept it.
All the others? Not so much. Unless you actually have dual citizenship of course.
