Tombstone
3:10 to Yuma (newer version with Bale, Crowe, Foster)
The Good, The Bad, and the Ugly
Desperado (glad someone else mentioned that one even though it's non-traditional)
The Way of the Gun (also non-traditional, but very much a western-type flick)
I really like movies that bend genres, and No Country and Logan are two incredible films that cross into western territory without the typical Wild West period piece timeframe.
I really want to see Hell or High Water...still haven't had an opportunity to do so.