For me, it's a tie between Atom Heart Mother and A Momentary Lapse of Reason, and that's because AHM sounds so silly at times and AMLOR sounds so dated. All the good parts of AHM are in the middle, whilst it's bookended by horrible tracks. The suite was an experiment, but a bloated pretentious experiment. The only redeeming part of the suite is some cool sounding Gilmour solos, and Mother Fore. Alan's Psychedelic Breakfast is really gimmicky. In all aspects, AMLOR was a Gilmour+Others production, and you can REALLY tell it's an 80s album by its production and sound, which is something you don't find in many other Pink Floyd albums.

Good Tracks: Fat Old Sun, On the Turning Away, If, One Slip

Bad Tracks: Alan's Psychedelic Breakfast, The Dogs of War, A New Machine, Yet Another Movie

But neither of those albums have my least favorite Pink Floyd song.