Ford is always great, although he seems a little out of date today.  For my money his top ten would be as follows, in order of greatness.
1. The Searchers
2. The Man Who Shot Liberty Valance
3. The Grapes of Wrath
4. The Long Voyage Home
5. My Darling Clementine
6. Mister Roberts
7. The Whole Towns Talking
8. The Last Hurrah
9. Rio Grande
10. Young Mr. Lincoln