^Yuck. Sorry but I don't get the hype/credit or whatever that people like that song. Weird and boring noises and iffy vocals for me.

EDIT: To the 'Welcome To the Machine' vote by Alfred.

"Wish You Were Here," though it was tough choosing.

yes,very hard to choose indeed,but i'll go with Wish You Were Here.

Us & Them

time / the great gig in the sky. i know they're two separate tracks but the great gig in the sky works too well as a coda for time to leave it off. i love how they use a voice instead of a guitar for the lead on that piece as well. those two pieces combined form what i consider to be one of the best representations of floyd i can think of. it's what i would play to someone who hasn't heard them before to introduce them to the band. you get a feel for their experimentalism, psychedelia, waters' introspective lyricism, and their ability to change the mood of their music without sounding convoluted.

echoes is a close second.

wish you were here
so simple, yet so good.

i would say time, but i've been so into Pigs lately so I vote Pigs

Wish You Were Here hands down

Dogs it is here as well.

Astronomy Domine. It's crushing.