pick ONE, that is the hard part
passing over a lot of more obvious - and somewhat deserving songs -
I will go with Out In The Country
name your very favorite 
I’ve always had a soft spot for An Old Fashioned Love Song.
I liked most of their hits. My favorite is either “Shambala” or Harry Nilsson’s “One.”
I can’t pick an all time favorite. They’re all pretty good.
Today I really like Liar.
I also like all of their hits.
I’m going with Mama Told Me.
mmm
then you should go with it 
I love so many of their songs, but my heart immediately went to Never Been to Spain. Mama Told Me is a close second.
That’s a tough choice. It’s a tie between Family of Man, and Never Been to Spain.
I like Celebrate and I’ve always favored their version of Chest Fever.
Joy to the World
It’s one of the first barre chord songs I learned on the guitar. I still occasionally play and sing it for fun. Written oddly enough by a folkie, Hoyt Axton.
My youth pastor used to do this version for us. Starts Jeremiah was a Prophet
“The Show Must Go On.” Written and originally recorded by Leo Sayer, radio stations usually fade it out at the 3 minute mark–you’ll see why. The cover of the album that song was on was kinda controversial; you’ll see on the video some creature giving birth to a vinyl record in an OR with the band playing “doctors.” What happened next, you ask? Later (and maybe original) versions had a HUGE Band-aid plastered across 80% of the front–at first, it was a Band-aid sticker and you’d kill yourself trying to peel it off to see what the hubbub was, bub. Later pressings had the Band-aid embossed into the cardboard over the original artwork. Whole lotta nuthin.
Same here.
For me, definitely “Shambhala”. Gorgeous song with beautiful harmonies.
Another vote for Never Been to Spain
Also worth mentioning: Easy To Be Hard.
mmm
I never pick a cover, but covers are all they did.
So: Never Been To Spain
and Liar
I liked Family of Man but it’s a little slight.
Eli’s Coming was very big when I was in business school in 1970.
I like Family of Man, too, but what do you mean by slight?
my number two has to be Joy To The World. so much for only one!!
One – far and away my favorite.