Maybe I am old and weird for MMPOG's (57 last November) but one of my all time favorites was Paint Your Wagon. One of the few musicals I ever enjoyed. Imagine Clint Eastwood, Lee Marvin, etc singing??
The Villain was also a nice twist on westerns. Kirk Douglas is the villain with Arnold Schwarzenegger as the "Handsome Stranger" and Ann Margaret as the .......? One of the few total comedy westerns.
To actually declare a favorite or best is tough for me since I lived through the era of great TV westerns; Maverick, Gunsmoke, Have Gun Will Travel, Sugarfoot, Cheyenne, Bronco, Bonanza, The Lawman, Yancy Derringer, etc etc....