One of my favorites is The Wings of Eagles. It's the life story of Frank 'Spig' Wead, one of the original naval aviators who later wrote screenplays for John Ford.
I enjoyed The Searchers and The Quiet Man also. I haven’t seen the Wings of Eagles,except for a small part of it.There are very few of his movies that I haven’t enjoyed.
Other Duke favorites: Back to Bataan,The Comancheros,The Alamo,and The Longest Day.