Robert Redford as a mountain man is explanation enough, but seriously, this was the first western movie I felt was authentic. Loved the location, costumes, Jeremiah's struggle to survive in the wilderness, and his relationship with the Indian squaw. This is by far my favorite Robert Redford western.
Two Mules for Sister Sara
LOVED this movie and cemented my love of Clint Eatwood westerns. Though this differed slightly from what he was doing at that time. But ranks up there as one of my favorite Clint Eastwood westerns.
This is a more recent movie but is one of my favorites. Again, I love how authentic the movie feels. I love the strong protagonist and the extent she will go for her children. Love the mystery and suspense the opening scenes deliver.