Dark Side of the Moon and The Wall are both easily in the top 5 of albums whose tracks are played most on the radio, and Wish You Were Here is probably somewhere up there too.
They were a band that regularly engaged in lengthy, "self-indulgent" instrumental noodling, while almost never displaying raw chops on the level of the instrumentalists of the more popular prog rock bands of the day.
They were one of the most technophilian bands I've ever heard in my life, relying on sound effects like mad and featuring all kinds of processed keyboard and guitar noises, yet it is extremely rare to find somebody nowadays who considers a classic Pink Floyd album "artificial" sounding.
Yet despite their massive success and following, and despite an ever-growing number of people who have a strong familiarity and love for the band's whole history, the % of music fans who really know the group is pretty small.
If one were to ask a typical classic rock fan off of the street to name albums that Pink Floyd had done, 95 times out of 100 the answers would be restricted to Dark Side of the Moon, The Wall and Wish You Were Here.
The classic albums did a good job of refining the band's earlier ideas into something more easily swallowed by the general public, but many of these ideas were, in my opinion, done just as interestingly on the earlier albums, if not more so.
One thing that I've never wavered on over the years is that "Echoes" is the best thing Pink Floyd ever did, and many of the more outstanding elements of that track were at least used as crib-notes in bits and pieces later on.
Roger Waters took it upon himself early on to be the band's "leader," but while it is true that Pink Floyd eventually became, in essence, his backing band, the group was very much a "democracy" for a good number of years.
Roger may not have been the main songwriter for most of the band's life, but he was certainly the band's dark, bitter soul, and he brought a number of things to the table.
History has done a really strange job of treating the band's legacy, though.
On the one hand, anybody who has ever listened to a classic rock station has had some level of exposure to them.
Moving onto the band members themselves, I'd have to say that Pink Floyd had one of the most fascinating internal dynamics of any band that I know.