For myself it was pretty memorable ones.
1/ Van Der Graaf Generator…1975
2/ AC/DC with Bon Scott…1976
3/ Blackmore’s Rainbow with Dio, Blackmore and Powell…1976
After those it’s kind of a blur of live shows as I od on anything and everything.
But those three still have vivid memories even now!
Dave Clark Five - 1965 - Charlotte, NC
Billy Stewart - 1967 - Raleigh, NC
Chicago - 1973 - Columbia, SC
The peddlers -, late 60’s I think I was 9, had to get my dad to take me…Auckland NZ
The B52’s I think maybe was around 1972/3 what a hoot, Wellington NZ
Grace Jones ~1974 a free concert in Wellington, NZ when she was a total unknown…blown away!
My parents refused to take me to any show so had to wait until I was 16 and took myself on my trusty Honda C50 step through 
Spear of destiny
New model army
GBH
As I try to remember, I think this was the order of my first three
Adam Ant (Genuinely can’t remember the venue)
Hanoi Rocks, The Marquee Club, Wardour St.
Dire Straits, Hamersmith Odeon
I went on a Honda MT50, ruined my Mohawk.
Dizzy Gillespie - Gatineau Hills, Quebec
Miles Davis - Detroit
Sonny Rollins - Ottawa Jazz festival
Iron Maiden (number of the beast tour)
Depeche Mode (construction time again)
Ultravox (can’t remember what tour)
All at St David’s Hall (Cardiff) which was pretty much the only venue in the city at that point.
My first two were in Derby which was about a 12 mile ride which on an old clapped out C50 with possibly 1 candlepower headlight was pretty entertaining all on its own right…lol
Rainbow was at Bingley Hal, Stafford and that fortunately had a bus organised from our local town although we missed it for the trip back home and had to thumb it back, which is a whole nother tale!
Oh dear, I can’t remember. I know the first concert was four guys and a reel-to-reel tape player at the Hammersmith Odeon in '82… they were the original line-up of Depeche Mode. I saw a lot of live music and theatre after that.
Def Leppard at the Sheffield Show, just before releasing their first single ('79?). Probably followed by The Ramones at the Top Rank Suite and either Gillan or Whitesnake at the City Hall.
Never ever got to see Whitesnake in any of their configuration 
Ramones - lucky thing.
Tower of Power, Marysville, CA
Bachman-Turner Overdrive / Bob Seger, Jackson, MS
Dan Fogelberg, Oxford, MS
Regret missing what would have been concert #2. Santana headlined a street concert during my college freshman orientation weekend at CSU - San Jose.
All such a long time ago for many of us but the dates can be looked up on this site, which looks quite comprehensive:
U.K. Events
The Four Tops - The Guildhall, Chard, Somerset - 1967 (?)
Status Quo - The Van Dike Club, Plymouth, Devon - 1969 (?)
The Groundhogs - The Manor Pavilion, Sidmouth, Devon - 1970 (?)
Great site but loads of “gaps.”
Memory is a little hazy, but I think it was most likely:
Steeleye Span - Edinburgh Usher Hall, 1974 (?)
Nils Lofgren - Edinburgh Usher Hall, 1975 (?)
Santana - Edinburgh Apollo, 1976 (?)
Janis Joplin w/Big Brother and the Holding Co.@ Grande BallRoom ‘68
Santana -Detroit ‘69
Neil Diamond - Masonic Temple Detroit ‘70
There were more at the Grande Ballroom in ‘69