The problem with picking the favorite John Wayne movie, is that he left such a hugh body of work. Dam few stinkers, but If I had to take just one, it would Be The Searchers. The Duke is still well up there on the top 10 actors list and considering that ha whole generation has been born and come of age since his passing says a lot. Then again when there were Directors like John Ford, Henry Hathaway around, its was easy, and easier still they loved the country and it showed in the movies they made. The Dukes last movie "The Shootist" is a fine film, but that was in theaters in 1976 so it was shot in 1974 - 1975 time frame, he may have gotten the script earlier than that. Its dam near 40 years ago! Old guys like me who grew up on the Dukes movies remember how it was to go to the movies and what the country was, hell I don't even recognize the country these days.
