Best progressive rock album side

@sns 

By the way, I'm a boomer NOT solely dedicated to reminiscing. I regularly stream music from virtually all genres and eras, prog rock stands up over time as legitimate genre. Some great musicianship, composition and explorations, certainly there can be excess, but what genre doesn't have it's filler.

I am also a boomer, but my tastes in music have never stopped evolving.

The vast majority of people have their tastes in music set by their early 30's. Most people have a large nostalgia component in the music they listen to. As you mention about reminiscing, many people seem to want the music they listen to, to be music that was part of the 'soundtrack' of their youth.

Music tastes stop at age 30

The things I like in music are, most or all of the following* (no particular order): high level of musicianship, complexity, deep and broad range of emotional and/or intellectual content, avoidance of verse>chorus>bridge song format, (usually) extended song structure, avoidance of an obvious 'hook'.

Within those attributes, I am pretty genre agnostic, so to speak. As long as music has all or most of those attributes, I will most likely enjoy it.

Since I enjoy music with these attributes, more than any particular 'style' of music, I was able to get into prog-metal and technical-metal in my 50's, despite not really being a metal fan previously. 

I was also able to get into modern classical music in my 50's, despite not being much of a classical fan previously.

All the following have all or most of those attributes, and are the genres and subgenres I listen to. Prog and most of its subgenres (avant-prog, Zeuhl, Canterbury, classic prog, prog-metal, technical-metal), jazz and many of its subgenres (post-bop, fusion, avant-garde, M-Base, chamber-jazz), and classical (avant-garde, serial, modernism, contemporary).

Yes, I still listen to plenty of prog from the 70's, but it is not about reminiscing or nostalgia for me. Either the music holds up on its own merit, or it doesn't. But I also listen to plenty of recent prog as frequently as the 70's stuff.

*it's not as if I consciously chose to only like music with these attributes, I just noticed at one point, that music that did not fit them, was uninteresting to me

@sns I think I remember listing Bundles.  I’ll go back and check.  

There are a lot of late British Invasion bands mentioned in the second/third pages of this thread that I just did not enjoy.  I gave good listens to Humble Pie, the Soft Machine, the Incredible String Band, and Procol Harum. I even saw several of them in concert, mostly as the opening bands for more major acts. I found the bands overwrought and under-inspired. On the other hand, I truly enjoyed the Hollies. Their harmonies may have been Beatle-esque but they did 'em one better.

@spiritofradio Yes, you did mention Bundles per Soft Machine.

Some of the entries I'd not considered as prog rock prior to looking up definition of the genre. Far wider based than I thought based on these various definitions.

As for prog rock bands live. I saw any number back in the day, yes, many didn't live up to studio recordings. The major issue as I saw it was inability of technology as it then existed, to replicate studio sound. Melotron notoriously difficult to set up, keep in tune. And then, recall these were mostly pretty extensive studio productions, pretty difficult to replicate live back in the day. One can't judge these bands by live performance only, production values very important component of the music. For some, highly engineered and heavy handed production are the antithesis of good music, for me perfectly acceptable for this genre. Doing the same thing to straight rock, blues based rock or other genres ruins it for me.

Some genres benefit from direct raw emotion no frills recording allows, not the same for prog rock. For me, prog rock entices through manufactured soundscapes for the aural senses,  and mind journeys that invite introspection and thought. Rather like classical and various forms of jazz in inviting the mind journeys. Hearing some Art Blakey and/or Glenn Gould  juxtaposed to the right prog rock makes for a nice listening session in my book.