If you had access to a time machine, what concerts would you go back to see?

I'd go back for:
Springsteen 1976, Palladium Theater NYC.
Blondie 1976, the Village Gate.
Led Zep 1977, MSG.
Roxy Music 1983, Tower Theater Philly.
Sisters of Mercy 1984, The Ritz.
Buddy Rich w/ Maynard Ferguson ~1975, Felt Forum NYC.
Elton John w/ John Lennon 1974, MSG.
https://youtu.be/JtL_w62Y2RU

Benny Goodman January 16, 1938 Carnegie Hall New York

Stravinsky May 29 1913  Théâtre des Champs-Élysées Paris

Jimi Hendrix Band of Gypsies at the Fillmore East New Year’s Eve 1969! Instead I and three friends from Greenwich High went to the Dead show there a week earlier! I could easily have bought the Hendrix tickets when I went down to the Fillmore box office four weeks earlier! $3.50, $4.50, $5.50 - early or late show! Instead I got three tickets for the Dead early show. 

Creedance Clearwater at Woodstock, August '69! I had to be at work that weekend so no could go! 

The Allman Brothers Live at the Boston Tea Party. The first and best concert I ever saw. Duane was still alive.

The worse? Bob Dylan. He was in is country phase back then. We left after four or five numbers. It was pitiful.

Top concerts = The Dead (when they were hot), Little Feat, Radiohead, Tina Turner, Pat Benatar, The Stones (when they were hot), Death Cab for Cutie (what a name?), Richard Thompson Electric Band, Richard Thompson Solo, Carmina Burana, Beethoven's 9th