This is going way back, but when DH & I were planning our wedding, we went to a "bridal fair" event where you can meet a lot of vendors in one place. Not one but THREE of the DJs there told us that the Theme from M*A*S*H* was in their top five list of most requested first-dance songs. WTH??? (The title of that song is actually "Suicide is Painless".)
FWIW, my BIL was puzzled when his bride's father put his foot down and insisted that they would NOT be leaving the ceremony to the strains of Billy Idol's Rebel Yell.
DH picked our first dance song and would not tell me what it was, he wanted it to be a surprise. It was Clapton's Wonderful Tonight (which was sweet, but turned out to be a bit prophetic, because DH did have a bit too much to drink that evening, LOL.)
Both of our Dads died before we got married, but I know that Jimmy Buffett's Little Miss Magic has since become one of the most popular Father-Daughter Dance songs in the US, partly because it's sweet, and partly because it has such a simple tune that even men who are hopeless dancers can manage it.
I don't think I've every encountered Country Roads at a wedding (and now it's forever associated in my mind with land mines thanks to Kingsman: the Golden Circle), but on the subject of John Denver, Grandma's Feather Bed used to be a popular sing-along when the guests got good and drunk late in the festivities.