This thread is impossible. I was born in the 80s and used to do about 30+ gigs a year on average. I was lucky that my first two gigs were U2 on the epic ZooTV tour, and Nirvana before I was a teenager.
Seeing Oasis for the first time also on the night I got my first fake ID in a snowstorm was a great night.
First Ashcroft, Coldplay (Parachutes), McCartney...
Jamiroquai in Montreal 2005.
Arctic Monkeys for $11 with a couple hundred people was rather ace. In Miami 2014 was a superb trip.
Osheaga 2015 was amazing.
Too many though...
A good thread might be who haven't you seen, surprisingly. Answer: Radiohead.