That was a hard nut to crack, because there are so many great films in that genre.
I can't possibly cut it down to five - so here are my ten favorites:
1. THE FAR COUNTRY (possibly the greatest of the Anthony Mann/Jimmy Stewart collaborations)
2. SHANE
3. MY DARLING CLEMENTINE
4. FRIENDLY PERSUASION (perfect casting, perfect directing, everything's perfect - one of Coops very best)
5. BUTCH CASSIDY AND THE SUNDANCE KID
6. HIGH NOON (sorry, Duke - but I still like it)
7. THE MAG SEVEN (lots of fun - and it has McQueen)
8. GUNFIGHT AT THE OK CORRAL (the chemistry of Lancaster & Douglas - and the ballad of Frankie Laine)
9. WILL PENNY (something of a change)
10. COWBOY (Delmar Dave's and Glenn Ford's best work - very authentic)
so where can I put THE PROFESSIONALS, BEND OF THE RIVER, 3:10 TO YUMA, THE WESTERNER, THE LIFE AND TIMES OF JUDGE ROY BEAN, and THE GUNFIGHTER - they belong in my 10-best-list, too! 
