They're all kind of landmark albums for the Floyd if you consider the
subject. I mean, Piper was Syd Barrett's baby, it was what established
Floyd in the world of recorded music. It was a ridiculously successful
album so it's not just a landmark for Floyd but for music in general
as well. Dark Side of the Moon is something like one of the top
selling albums of all time if I'm not mistaken, and it's arguably the
"best" Pink Floyd album there is. Then you have the Wall, which is
Roger Waters' brainchild, and it signifies a complete turn for the
band in general. It's really the beginning of the end for the band,
despite being a musical masterpeice. By the time the Final Cut had
been made, the "Pink Floyd Sound" had been completely eradicated...

It's true that most people probably like one or two but not the third.
They are very radically different from each other in terms of style,
meaning, and mood. Unless you're a Pink Floyd Fanatic, of course, and
even then us Fanatics have our albums which we would rather skip out
on... Relics and The Final Cut for me...