Pink Floyd is the sountrack to when I'm tripping I think Floyd is better. Echoes is the ULTIMATE trip song and DSOTM is the only album I can listen to front to back.
I liek Zepplin but sometimes there are too many "OOOOOOOOOHHH BAAAAAABBY" and other things robert plant screams randomly and it gets annoying.
Zeppelin gets down harder. Theyre posessed with a powerful ingenuity of rhythm and melody. Most of the popular stuff is just scratching the surface. Try 'In My Time of Dying', 'White Summer/Black Mountain Slid', 'Nobody's Fault But Mine' or Achilles Last Stand'. Floyd is definitely more avant-garde for the time period. Beautiful albums, one must experience their records whole because the music is just tied so well together.
Zeppelins just has a more powerful energy behind them.