My favourites are the ones that pay homage to the landscape of the American west,some of which have already been mentioned....if I had to pick one,I couldn't......if I could pick three,they'd probably be:

3.   Song of the Trail [Stan Jones]
2.   Everlasting hills of Oklahoma [Tim Spencer]
1.   Man Walks among us [Marty Robbins]

I visited Arizona for the first time recently,was deeply moved by the
desert,mountains,vegetation,etc....I begin to understand why Bob Nolan and so many others were moved to portray that country in almost mystical terms....I thought of Marty Robbins[Arizona born] and the song mentioned above,which was an "environmental" warning of sorts,far head of it's time....he and Bob Nolan recorded it on Nolan's one and only solo recording in 1979,shortly before they both left us........