@Hal Pollner Shug, he could whisper sweet nothings to me all night long using that. "High squeaky" voice.
I'm never good at choosing the one best. Sam Elliott and James Garner have been mentioned and I agree that they were good. I'll add Bruce Dern and Gabby Hayes.
One of my most favorite western actors has to be Randolph Scott. He played in a lot of westerns (and if he was in other movies besides westerns, I guess I don’t remember them), and I loved his beautiful flaxen-maned chestnut horse, Dollar. We had movie matinees each weekend back when i was a kid, and most of them were westerns, which was (of course) my favorite because I loved horses and cowboys. Probably my most favorites were Audie Murphy and Jimmy Stewart. Audie Murphy was mostly in westerns except for the famous war story about him (To Hell and Back), and jimmy Stewart was a very versatile all-around actor. His role in Broken Arrow , along with Jeff Chandler (another great favorite of mine) as the Indian agent in love with the beautiful Indian Maiden, has forever been one of my best loved western movies.
For your edification, here is Randolph Scott: Nobody could play the U.S. Marshal any more convincingly! Hal
Garner was too "Hollywood Handsome". Real cowboys had defective facial characteristics, unlike the "pretty boy" wranglers. This is why I like the Western actors who play the "heavies", like Lee Van Cleef. Give me a rugged, scarred mug any time! Hal
Randolph Scott was in at least one movie with Joel McCrea. (Ride the High Country?). I always liked Joel McCrea better.