Ray Charles and Willie Nelson, "Seven Spanish Angels". I love this because, in addition to its gorgeous melody and the fact that the two performers here are, well, geniuses, the song invokes the folklore of the American West that I like a lot when used in country music.
Eddie Rabbitt, "Every Which Way But Loose". Yeah, the title song from the goofy Clint Eastwood movie (which I like, thank you very much). It too has a wonderful melody, Eddie Rabbitt's voice was fantastic, and this song has a slow, sad sensuality to it that I like when country is able to do it right.
Johnny Cash, "Ring of Fire". I could have named any of, oh, five hundred or so Johnny Cash songs. The man was a miracle. I choose this one because I love its rhythm -- this is a song that has a hitch in its step that at first you don't really even notice, but try walking along to it: you'll find that the beats end up on different feet. (Seriously.)
Jo Dee Messina, "I'm All Right". With newer country music, I tend to respond to female artists more than males these days for some reason. I think Jo Dee Messina's voice is amazing, and this song's lyrics are cleverly used to relate one half of a conversation -- but that's really all we need.