I'm sure we've had this conversation before, but I thought the TV adaptation of Lonesome Dove was one of the best things to come out of the US. The characters spoke in McMurty's prose style, much as I believe people in the Old West would have, and the personalities were totally unlike anything I had come across in Western genre storytelling, though probably True Grit came close - good and evil less accentuated, no black or white hat delineation.
McMurtry adapted the screenplay for Brokeback Mountain, by the way.