I'll give you Cohen and U2 but Neil Diamond? Sweet Caroline!m
Any thoughts on Simon & Garfunkle?
My first thought on Neil Diamond was "Forever in Blue Jeans" but there's something about "Play Me" that for me sums up what/who he is. I think the reason I can't go with "Sweet Caroline" is 'cause I simply don't like it - it's kinda what makes this exercise interesting as a signature tune should transcend personal taste.
As for Simon and Garfunkle - has to be "Sound of Silence"'
You have brains in your head You have feet in your shoes You can steer yourself any direction you choose. You're on your own and you know what you know And YOU are the one who'll decide where you go Dr Seuss