RUSH!!!
Rush, Rush, Rush and Rush!
You left off Sam The Sham and the Pharoahs.
I want to live in, or at least visit, your alternate universe where they are one of the biggest music acts of all time.
Beatles and the Who.
My other is Neil Young and Crazy Horse.
Also belong: Steely Dan, Queen, Allman Brothers, Jethro Tull.
mmm
ETA: Bruce and the E Street Band anyone?
I voted for the Beatles, but they’re actually in the second tier of my favorite major groups, behind my personal Holy Trinity of Electric Light Orchestra, Queen, and Yes.
My three favorite bands on this list: Genesis, The Who, and U2.
Rush, and R.E.M.
I was equally surprised when both bands decided it was time to retire, as in not at all.
Don’t forget about Zager & Evans, and A Taste of Honey. 
That wouldn’t be a very interesting poll, as Parliament/Funkadelic would be the clear winner.
Followed by Yes. 
Since we are talking about “mega” groups I would like to add Megadeth–(OK maybe not them because they really didn’t have much mainstream success).
'Lil Red Riding Hood is a classic and one of my favorite songs from the '60s.
The Beach Boys are one of my favorite bands of all time and the Who are in the top 10. Nothing else from the list makes it.
I chose the Stones because they had a number one album in six different decades. If a band spans that length of time yet puts out number ones they must have their finger on the pulse. Mick is now 78? Yeesh!
I chose Fleetwood Mac because they keep plugging away etc. On guitar…
Billy Burnette and Michael Thompson
Dave Mason was also in the lineup for one of their albums.
They did quite well considering the timing of their switch to a more commercially-friendly sound was in the midst of peak grunge. They were just following Metallica’s lead, but still they were successful at it. Countdown to Extinction and Youthanasia were #2 and #4 albums, respectively.
If anything, their problem is they were too prolific; they put out a new album every 2-3 years from their beginning in 1985 all the way until 2016, and lots of live albums and compilations in between. Their product is very diluted.
Like, whoa man, I only listen to bands no one’s ever heard of… daddy-o.
.
(I voted Other because I scrolled through my phone and realized none of the music was by even a Mini-Mega Group.)
Most of ‘my’ music is lesser-known bands from the British Invasion, other countries, or current stuff I found on YouTube.
Or here on the Dope… all the great covers linked to in so many threads.And the We’re all in the mood for a melody" thread is wonderful; I’m working my way through the deep cuts of a cool jazzy band (WOODS) right now…
My “Other” is Queen. The first two are Beatles and Zeppelin.
I meant to add a few others (honorable mention) that I had considered. Not that sales are the be-all end all, but subjectively I would have imagined from the airplay and general popularity that these sold better.
Boston: 75M sold
Chicago: 40M
Alice Cooper: 50M
Foreigner 80M (I can’t hack their lyrics)
Kinks: 50M
Mamas and Papas 40M
Moody Blues 70M
Steely Dan 40M
Styx 54M
Three Dog Night 40M
Toto 40M
ZZ Top 25M
Nice:
Polyphonic Spree!
My three:
Rush
Pink Floyd
Queen
(I don’t think the Alan Parsons Project counts as a “megagroup,” but if they do, they’d bump Queen.)
My “other” for a fourth pick would have been R.E.M. (I also love me some Jethro Tull, but I’d admit they’re not quite a “supergroup” by this poll’s standards). My top three were Beatles, Stones, and Zep. I know, predictable, but honestly their output would be the most represented in my “desert island discs.”