I'd have to say, in order:
Wish You Were Here
Meddle
Dark Side Of The Moon
Animals
The Piper At The Gates Of Dawn
Ummagumma
All great stuff. I saw them live in 1976 on the Wish You Were Here tour at Roosevelt Stadium in NJ. I was psychedelically altered at the time, and it was absolutely amazing. Had I not been, it still would have been great. And they did Echoes, which to see live is unreal, complete with CO2 fog rising on the stage. In my altered state, I may have as well seen God.
I never really got into their later stuff, but they're still one of my all time favorites. I still enjoy cranking up One Of These Days (to 11) and standing between the speakers in the livivng room, and just listen.
Baz...thanks for the Video. And up yours, Hard Drive.