Favorite: Blue Sky
Best because it encompasses all that is R&R: Stay With Me
I previously posted my vote that "Gimme Shelter" is the best Rock & Roll song ever, and I stand by that.
However, "Take It Easy" by The Eagles may be my all-time favorite song. The lyrics to that song are pure genius, particularly:
Well, I'm a standing on a corner in Winslow, Arizona and such a fine sight to see
It's a girl, my Lord, in a flatbed Ford, slowin' down to take a look at me
I just love that song!