Here's my X story.
Went to see Warren Zevon at the Beacon Theater in NYC, I think it was 1987. X was the opener. I didn't know them at all, except that I thought I'd read somewhere that the critics liked them. I wasn't really into punk at all. For some reason, I thought they were a British electronic new wave type band, like Depeche Mode.
So, they take the stage and absolutely killed it for whatever time they had. Exene was manic on stage, and she had to be 7 months pregnant. I was pretty much floored, not only by how good they were but how unexpected they were (for me). The next day I started buying their music and they've been one of my favorites since.
Other concert high points:
Springsteen, in '84 or '85, Born in the USA tour, at the Meadowlands in NJ.
Springsteen in 2016 at Madison Square Garden. With my wife and kids (yeah, I'm getting old).
Jason Isbell, June 2017 at the Beacon Theater, NYC.
The Mavericks.
Los Lobos.
Drive By Truckers/The Hold Steady, June 2014 on Long Island.
Low Cut Connie.