As for absolute size, I will have to go with either Coleman in his 2003/4 versions or Jean-Pierre Fux. Actually, Fux seemed to have quads that were as big as Coleman in his 280+ lbs form, but with better separations and a roundr shape.
As for the best quad of all times, that's a tough one. Methinks either Paul DeMayo or Benffato the best overral legs to me in terms of symmetrical development as well as aesthetically. Platz's legs were amazing except for you thing: they're stumpish, and I don't like that.
SUCKMYMUSCLE