The best one I went to, was Jeff Beck at the Capitol theater is Passaic NJ. He had Mahavishnu John McGlaughlin as the "other" band. At the end, they jammed together. It was awesome.
Next best was David Sancious and Tone, at the Fairleigh Dickinson Univ. campus in NJ. This band was only 3 members, and were so unbelievable in their Fusion capability. If you have never heard David Sancious, you need to listen to his older albums, like "Transformation: The Speed of Love". You won't believe it.
Next was Frank Zappa, at MSG Felt Forum, in NYC. It was the Halloween concerts of 72,and 73. If you have never seen Zappa in the Halloween concerts, you really missed something. In 73 he came out dressed like Cher, with a long black wig.
Then there was a stadium concert that had Eagles, Seals & Crofts, and a couple others. This was back before Joe Walsh joined them. At this concert, at a mid-point, they said,"We'd like to introduce our friend, Joe Walsh". They proceeded to rock out a heavy version of "Rocky Mountain Way" that was the best I ever heard. Totally awesome!
That's my 5, including the 2 Zappa Halloween concerts.