As an audience member?
For me it's a tossup between three. The Roxy Music Country Life tour, Little Feat Dixie Chicken, or Gentle Giant touring Free Hand. Three shows I am amazed I had the opportunity to experience.
How about you?
All About Eve, 1989, pretty much the front row. So great I passed out. Ok, maybe I had flu and went anyway and it wasn't entirely due to my crush on Juliane Regan.