These are at the top of my list:
Pink Floyd
Yes
Rush
Alan Parsons Project
Kansas
Styx
Atlanta Rhythm Section
ELO
Moody Blues
There are others but these are my favorites.
Atlanta Rhythm Section? Err, wot?
That being said, you did mention the Moody Blues where I don’t think anyone else had. That raises a point, in the realm of barroom arguments along the lines of “first true rock and roll song”, “first metal band”, “first true punk band/album”, and so on. There’s always a tipping point, and some would argue that the Moodies were it, if not actually being the first to represent the genre, before Crimson. Even though not the first to use a Mellotron, they were the ones to bring it to the forefront(of course it helped that MB keyboardist Mike Pinder was involved in the development of it). I personally could see it either way, but I was surprised that they hadn’t been name checked otherwise. The earliest Genesis material(produced by Jonathan King)was under their influence.
THEN...another conspicuous in its absence item would be no mention of German bands(someone did come up with Triumvirat, but I never heard them as being all that original, just ELP wannabes). One band who WAS original was Amon Duul, primarily the second version, but they(and others)get tagged as “krautrock”, which is just lazy thinking. What krautrock means to me is something far more minimal, an actual antithesis to chapter and verse prog. Amon Duul were pretty out there, confrontational, you could sometimes hear strains of Zappa. And speaking of ‘out there’, there’s Tangerine Dream, but once again they get marginalized into not only krautrock, but the separate but equal genre of space rock, where you might find Hawkwind, sometimes even Floyd. But then again, TD was more space than rock.
