I’d put James Stewart second, myself.
Oh, Stewart’s westerns he did for Anthony Mann are terrific. I just never tend to think of him as a primarily ‘western’ actor. When I first saw “The Naked Spur,” I was particularly impressed with Stewart’s performance, and I wrote him a letter to tell him so. And I got a nice little hand-written card back. A few years later, I met and had a long talk with the film’s scriptwriter, Sam Rolfe.
Although come to think of it, Randolph Scott himself wasn’t a primarily ‘western’ actor until after WW2. He was in a whole host of varied oddities, like the hero of the fantasy-adventure “She” (1935), and the semi-horror “Supernatural” (1933) with Carole Lombard, and even starred opposite Kate Smith in “Hello, Everybody” (1933). Not to mention some comedy-musicals, like “High, Wide and Handsome” with Irene Dunne.