Navajos for sure. I have no Navajo blood, it is Cherokee, Choctaw, and possibly Comanche, but someone in the group married a Navajo, there were several around. I was influenced by their ideas at an early age. One thing that impressed me was they were the only ones who actually spoke their own language. The rest spoke English, many spoke Spanish, and a few spoke French. But on the whole white rules and white culture had erased the native languages of the other groups.
Cherokees don't speak Cherokee language? I understand there is a written Cherokee language (courtesy of Sequoyah). There are websites that are devoted to teaching you to speak that language.