Best concert you've attended

There’s been a number of them, but probably it was The Moody Blues tour for the Octave album. They were good but the opening act was relatively unknown at the time, Stevie Ray Vaughan and Double Trouble. 
 

I have many others but thought I’d keep down to one best.

I answered this question on a similar post last year in more detail but as far as bigger concerts go, one that stands out was the 1984 Roger Waters Pros and Cons of Hitchhiking tour in London. Great crowd and vibe. Saw him again years later in Boston and the crowd was less amicable.

some of you listed all the concerts you have been to, that wasn't the question

While in high school I began going to the free concerts at an auditorium at Ohio State University during winter and early spring. Saw the Eagles at the  end of their tour for their first album. 2 or 3 months later they arrived at the same venue and played all of Desperado. Mostly acoustic instruments. Not only. Sound system there was always very good, and after all the many concerts I have attended, that's the one I'd pick.

Pink Floyd, Music Hall Boston 1973 DSOTM tour

Jimi Hendrix, Newport Folk Festival 1967

Jethro Tull, RI Auditorium 1971 Aqualung tour 

ELP, Boston Garden 1972

Led Zeppelin 1973 (I think) Providence Civic Center

Frank Zappa & Captain Beefheart, Music Hall Boston 1975

Yes, Providence Civic Center

Alice Cooper, Providence Civic Center

Sly & The Family Stone, Prov Civic Ctr (Sly was an hour late, but what a show.}

Black Sabbath, Civic Center

George Harrison, Civic Center

Carly Simon, Nantucket MA  

The Who, Boston Garden 1974

Plus, a hundred others.