For me it's tricky, so I'll mention a couple.
Jethro Tull numerous times in the 70s ... Ultravox in 79 opening for, and blowing off the stage, The Police.
And the greatest ... The Sensational Alex Harvey Band. If you have seen me play in circles you've probably heard my favorite story about Alex. I think this sizes up their attitude onstage.
They were opening for Slade in 1972. Slade is pretty well forgotten by most folks on this side of the pond, but in 1972 they were one of the biggest acts in the British Isles. No one wanted to open for Slade, it was dangerous, their fans were berserk. Alex saw no problem with it. One night was particularly tricky. At a certain point Alex walked up to the mike, and in his thick Scottish burr said "I've got some good news and some bad news. The good news is, this is our last song". The audience cheered, and cheered. Alex stepped back with his wonderful gap toothed wicked grin. And kept grinning. After a moment, the audience calmed down. Alex stepped up to the mike and said "the bad news is it's a fookin long one".
Much of Alex's early fan base was made up of folks who saw them on that tour.