I'm pretty sure we can all agree upon the eternal undisputed greatness of Pink Floyd.
I don't want to call the poll The Best Pink Floyd Song because, to be honest, I don't think there is one (I think there's a solid half dozen "right" answers here probably more.) and then it'll descend into arguing because we're all a bunch of bad MF'ers around here.

So I would like to ask that you pick three of them. I think that'll give us a good sampling of where things lie. I'll do my best to represent them and leave out any glaring omissions.
I'm lumping the live and studio versions together so as to not have a poll with 50 choices. If you want to call out the live version go for it.
I do think it would be fun if we posted YouTubes of these tracks.
Now Shine On You Crazy Diamonds!