I was a casual Floyd fan up until last year. That's when I decided to sit and listen to all of their output from the 70s. I couldn't believe what I had been missing out on all these years. I was amazed at how the music made me feel as a whole and just how well done their albums were.
I've yet to listen to their albums from the 60s, 80s and 90s (except for Pulse) aside from some random tracks, but I can't imagine them living up to what they made in the 70s.
My favorites in order thus far:
The Dark Side Of The Moon/The Wall
Wish You Were Here
Meddle
Animals
Atom Heart Mother
Obscured By Clouds