Would have to be Animals, the solo's in Dogs are amongst the best guitar solo's of all time. Obviously Dark Side is THE classic. Wish You Were Here and MEddle. The Wall has many moments.
Did'nt digest later than Wall or before Meddle really. Agreed with the point of Roger Waters 'taking over' in Radio Chaos and some of the later stuff is comparatively bland.
Also frying eggs and bacon on a track (which album was that? UmmaGumma?) although at the time funny, holds not much interest for me. Too Many Mushrooms!!! lol
A truly fantastic band. Certainly a big influence worldwide.