I think a Hoover Spirit canister would do well.
Not too bulky, and it was very light weight. Just add a more powerful motor, HEPA post motor filter, HEPA K bags, streamlined telescopic wands and give it an agitator on/off switch. The Quadraflex Power nozzle can return to the market as it was but with the better wands and a sturdier base plate so the agitator doesn't break the housing which was a common issue with those!
or
Eureka WorldVac, Express, Hoover Futura similar units.
Everything is on board, the canisters weren't heavy, power was good. What the units need are post motor filters, HEPA filtration, better seals and gaskets for bag compartment and motor housing, streamlined wand connections with cord similar to a Kenmore quick release on the wand. Canister wheels need to be rubber coated. The Hoover Futura could use wider front wheels and a squared off axle that doesn't rotate with the wheel and is more sturdily mounted on the power nozzle. Serpentine belt systems and large rubber coated rear power nozzle wheels so the nozzle can be tilted back and wheeled around the house.
Uprights- I think if more people knew that Hoover Convertibles were still around and available in a big box store and a HEPA A bag could be used, it would be received well. Everyday consumers don't check out the commercial market or see the words "Commercial" and don't think it's meant to be used in a normal home. They really weren't too heavy. Some people just want simple and the Convertible was. You can buzz around a home pretty quick with one, they do a great job cleaning and the bag capacity of a Type A is huge!! They're also not bulky like a Dyson and many other cleaners!
The Hoover Caddy vac was a neat idea because the attachment caddy was removable from the machine and could be stored on a door knob! Again a stronger motor for attachment suction.
Many consumers like Kenmore canisters but miss the quality. All of the new stuff has neat features but they are hell bound by circuit boards and power issues in the new bulky handle wand systems. I've read tons of reviews where the power nozzle no longer receives power after 6 months of ownership!
[this post was last edited: 3/26/2016-17:46]