some I actually saw would be hard to top
in 1979 I saw UFO with Priest opening. This was basically Unleashed In The East followed by Strangers In The Night, two of the best live sets ever. It's nice to be able to recreate whenever I want now too. Arena was only half full.
I saw the Screaming For Vengance tour too, with Maiden (and Axe opening- which is strange but OK since I liked Axe too).
or how about Wishbone Ash, Uriah Heep, Nazareth, and Blue Oyster Cult. They were all out of style then, so that one was also just half full.
Van Halen a week after releasing their first album, Journey (Greg Rollie era). That could have sold 50'000 tickets a decade later but it was Montrose headlining (not bad) so again just half full
a dream concert would be Alex Harvey Band (SAHB) and Sweet. Strangely I can't find any record of their ever having played together- although they must have, both being Scottish Legends of the 70's.