is this the greatest live band of all time?

This is like asking what is the best painting ever.....very subjective.
That said, there are many good choices in this thread and I would have a hard time arguing against The Grateful Dead.  The Who (1975) may have been the best concert I have seen, although Johnny Cash was memorable too.  So many good ones - I appreciate the artists who are energized to deliver their best performances in front of a live audience. 

@twoleftears , I saw the Zombies in 2017 at their N. American tour commemorating the 50th anniversary of Odessey and Oracle.  Colin Blunstone, Rod Argent, Chris White and Hugh Grundy were there and they sounded great - an awesome evening!

@yyzsantabarbara 
I saw The Who in 1975, Rush in 1976, but Santana not until the 1990's - all were great shows! Pearl Jam would have been a sweet show.  

@dwiphefl1128 

I kind of want to hear a band that sounds better live than on their records

I have seen many bands that fall into that category as I believe most musicians/artists are energized by a live audience.  I heard two of your listed bands during the periods you list and both shows were outstanding:

• YES - 1976
• Genesis - Lamb Lies Down tour