The thing I find with Mule Variations, though, is that it seems very self-conscious in including "everything"; it's almost Tom Waits-by-numbers, like he's sat down and gone "here's the rocker, here's the ballad, now a creepy spoken word piece"...it's a brilliant album, don't get me wrong, but it doesn't seem to have the flow and feel of some of his other works.
Which, incidentally, would lead me to say that, probably, "Rain Dogs" by Tom Waits would by my ONE album. It flows brilliantly from start to finish, is utterly timeless, unique, and overall just full of brilliant songs.
Honourable mention, though, goes to "Bone Machine" by Tom Waits, "Nebraska" by Bruce Springsteen, "The Velvet Underground & Nico" by The Velvet Underground, "The Queen Is Dead" by The Smiths, "Warmer Corners" by The Lucksmiths, and probably lots of other things.
I always quite liked the flow of Mule, I mean it starts out with a song that absolutely typifies his experimental style and gets the album off with a bang. The next song, Lowside of the Road, continues the feel but slows it down slightly, then Hold On slows it down further. The next few songs balance the ballads until Cold Water (my consummate drunken slurred song, many a night has ended with me and a friend walking arm and arm howling the lyrics at the moon on our way home from the bars) the spoken track splits the album, breaking it from the more traditional folky stuff and the more industrial. A couple ballads later Box spring hog wakes you up, Take it With Me me kills you and breaks your heart, and finally you are delivered when he invites you to Come On Up to the House.
Also I don't know how I missed mentioning Nebraska... on a side note that album has my all time favorite album cover.