Interesting that the clip you posted has Pernell Roberts in it...evidently before Bonanza days.
My nomination for the most dramatic western theme is Lawman....LOVE that song. Interesting that it's another Warner Brothers production, following the model of western themes with a male chorus doing the vocals.
By coincidence I just watched Eastwood's Pale Rider, in which John Russell (Lawman) played the unscrupulous leader of the enforcer "deputies".
Doggone it - can't make the window come up.....