Too difficult to pick one, so after a bit of reflection, although my first choice would have been the Beatles playing Get Back, it wasn’t a “proper” concert. I remember they were playing locally in the 60’s, but as my brother and I were too young we ended up going to a Pantomime instead. “Oh yes we did!” But that is all “Behind me” now. I did see McCartney live a few years ago, and would rate it amongst my top five most enjoyable concerts.
I considered Pink FLoyd, Genesis, Crosby-Stills-Nash-Young (together) although I’ve seen them separately. Woodstock would have been nice without the queues. A school chum actually went to the Isle of White concert

.
This brings me to my final choice. It is someone I was privileged to catch live in 2014. However, although this is also in my top five concerts, it’s not the one I’d go back in time for. It’s this one I missed

.