There was a thread yesterday on a private music forum I frequent asking for who we thought were "underrated" classic rock bands.
I immediately thought of Boston and Journey; who are much loved by the public, but much reviled by music critics, music snobs etc...
Some objected to this on the grounds that everyone knows those bands, and they get a lot of airplay.
Lots of other folks (mostly people in their early 20s) brought up a number of artists who are most definitely NOT classic rock; artists I love like the Ramones, the MC5 and husker du.
Others brought up Rush and King Crimson.
A couple folks brought up Queen.
Lots of folks brought up artists that didn't start making music until the late 80s.
Ok, so people were bringing up lots of great bands... Most of which are not classic rock.
I realized they have a definitional problem.
Most of these kids were clearly thinking something along the lines of "everything made before I was born is "classic rock".
Classic rock is not a chronological age, it's a genre.
In particular, classic rock is a broad class of subgenre sharing similar guitar and drum heavy styles, being blues based with progressive and pop influences; but not being too fast or too heavy and creeping into true hard rock or heavy metal, or too poppy and creeping into actual "pop" (and yes, those are very fuzzy lines often pushed very hard in one direction or another).
Prior to the early 80s, "classic rock" was in large part the genre generally called "album oriented rock" or "FM rock"; but the rise of consolidated radio networks like Clear Channel tended to focus the playlists on singles under 4 minutes from recognized popular artists (rather than the well known excesses of many 1970s albums and artists; both for better and for worse).
Classic rock primarily consists of music produced between 1965 and 1985 (with the vast majority between 1970 and 1980). Basically in between Oldies and New Wave, but not including Punk and Metal); or artists that became popular in that time period.
Just like "oldies" is still, and always has been, everything from Bill Haley to the British invasion (roughly 1953 to 1963). It is generally "birth of rock" and "pop standards" (including pop standards dating back to the 1930s), plus a little rockabilly, made for depression babies (people born between 1930 and 1945) by depression babies (with some exceptions, like Chuck Berry and Bill Haley, both born in 1925).
Similarly "Classic Rock" could also be defined fairly accurately as the popular rock music and artists (vs. straight up pop music) that the baby boom generation listened to from their teen years through their twenties. It was basically war babies and baby boomers, making music for war babies and baby boomers (every member of the Beatles, the Stones, and the Who, except Bill Wyman, was a war baby).
Notably, the early Beatles work is largely grouped into the Oldies, while everything Rubber Soul (1965) and later is grouped into Classic Rock. Oldies radio very rarely plays late Beatles; but classic rock radio often plays early Beatles.
In comparison, the Stones, the Who, the Kinks, the Yardbirds, and The Animals; all of whom released albums prior to "Rubber Soul" and who in those early albums were no "harder" than the Beatles; are almost never included in Oldies radio, but again receive lots of classic rock radio airplay.
There are certainly subgenres of classic rock; from Progressive hard blues (Aerosmith, Led Zeppelin) to folk rock (Bob Dylan, CSN, the band), to arena rock (Journey, Boston), to country/southern rock (Lynyrd Skynyrd), to genre blenders like Queen and the Eagles; but all are in the same classic rock mold.
If new artists play music in those subgenre, they will generally get played along with the older artists on classic rock radio.
Now, as to what constitutes underrated...
Rush and King Crimson are progressive rock. Queen, can't really be defined as any genre other than "classic rock" but along with Rush and King Crimson, they aren't underrated.
They are perhaps under-appreciated by the non-fan public (who may know a few tunes from each, but have probably never heard anything that isn't a widely played single); but for knowledgable music fans, they are basically taken as a given that everyone knows and loves their work if they are a fan of their genres (Queen, being a genre all it's own of course).
Also, I disagree with the idea that lots of airplay equals "not underrated". Music critics and music snobs LOATHE Boston, Journey, Def Leppard etc... All the arena rock types. You will never see them in "best of" lists, unless it's ironically (or a list by the listening public, who love them).
Now for some arena rock, sure they really weren't any good (Elo and grand funk for example. Good musicians making mediocre music) . But in the case of the true classics, that just isn't true.
Sure, some of Journeys songs or Bostons songs were sappy or cheesy, but a lot weren't; and you can't deny that Steve Perry and Tom Brad Delp were spectacular vocalists; or that Neil Schon and Barry Goudreau were great guitarists.... and Tom Scholz is an honest to god musical genius.
...but you'll never see Rolling Stone admit it.