Hmmm. Late 60's those big old steel bodied Kenmore canisters with their Powermates were about as good as it got. They were a little bit loud and crudely built in an endearing American way but durable and powerful (for the era). Sears went out of their way back then to always sell the most powerful vacuum on the market. Luxes of the era were quieter and more refined but it is hard to argue with the power (for their day mind you, not by modern standards) or the robustness of the Powermate floor brush. Sears has also always had a thing for providing a big dust bag and a long hose. Unfortunately lousy hose materials were their worst feature. The best part was their easy availability, price and service. There was a Sears selling and servicing high quality vacuums at reasonable prices in every town and city. No dodgy door to door sales shenanigans.
For earlier years, eh, Electrolux has always been consistent in making a top quality machine. Maybe one year someone else would outclean them on some "scientific" test or offer some trick feature, but year after year Lux sold beautiful quiet sophisticated exceedingly durable vacuums with competitive cleaning power, excellent attachments and let down only by a small dust bag capacity. Their modern iteration, Aerus, still does, but their prices are now ridiculous.