very difficult question to answer, the 1st to come to mind was The Clash on Broadway in the early 80's
but I also saw the Ramones at their hottest in the late seventies. ( it was at a party in the east village, they were great)
Bad Brains, Dead Kennedys and black Flag
all on the same bill, my shoulder was permanently disabled at that show and, well, other stuff I cant mention happened.
A Zappa Halloween concert at the Felt forum, we had a mini protest that really confused the NYPD we were all chanting "titties and beer" with the younger cops telling us "finally a protest we agree with"
Two different Dylan concerts spring to mind as well one during the Rodney King riots and another on sept 13 2001, you could feel the tension in the air on both of those nights.
Michelle Shocked taught me to play some songs when I was learning to play guitar, and having her invite me onstage with her during her early tours was really nice.
I got paid 50 bucks a day to be in the David Bowie Tin Machine video ( the first one ).
Peter Tosh in Central Park.
A lot of early hardcore punk shows were really awesome but there were so many, I was getting in free so I saw many shows week after week, day after day. Fear, Bad Brains,Reagan Youth, Black Flag, Kraut, Teen Idle,Agnostic Front, Cro Mags, Crucial Truth, War Zone, the raddicts, nausea, to many bands to even remember.
Its to close to call, some of the Clash shows, most of the Bad Brains and early Ramones are kind of tied.
In the mid eighties I was part of the NYC east village scene, all kinds of musicians and other artist would hang out in Tompkin Sq Park at night and there would be lots of jamming for instance one time Ivan Julian ( of Richard Hell and The Voidiods), a guy from a now unknown ( great ) band called
the cigarettes Michelle Shocked, me and some other guy jammed to a bunch of Hank Williams tunes that I had recently learned - they were all really nice to me as I was just learning. does that qualify as a concert? We were only entertaining ourselves.
I used to busk in the east village too, playing whatever I felt like, sometimes making great money other times all night for a cup of coffee.....
Come to think of it, the last few yrs I hardly play much at all, I want to start doing it again but A: no one to jam with B: Its like taking lessons from Sgt York and only having cub scouts to shoot with when I do find folks to jam with, I'm not saying I'm a great guitarist, far from it I cant read music and only know chords really - but jamming with folks who's interest go from the Rolling Stones to Dylan, Hank Williams and the clash is difficult nowadays. Its enough to get me interested in going back to NYC if they would only accept the gosh dang Constitution and stop discrimination against gunnies.