very hard, i'd have to say 'great gig in the sky' but most of the time i listen to them by album not by song, and even that is difficult to choose a favorite, but i think i would have to say the 'final cut' does it for me, or any roger waters album as i feel he was the true genius of the operation. but they are without a doubt one of my favorite bands.
Comfortably Numb but it has to be the Live version from Pulse but not the released version there was a very good Bootleg that is better and the version on there has a much longer guitar solo which i think is out of this world!
Couldn't pick out just one but favourites are: Fearless, One Of These Days, Time, Us & Them, Brain Damage, Wish You Were Here, one off The Division Bell I can't remember the name of.
Forced to pick one it'd probably be Fearless.
I'm always interested to see what people think of this: Dark Side is about 5 great songs interspersed with overrated filler material.
Shine On is my favourite but to be honest I like all their stuff from DSOTM onwards although I think The Final Cut is a VERY under rated album - they never play any songs from it live and I have seen them 5 times !