If you don't mind a somewhat heavy vac, have lots of carpeting, and want a nearly indestructable one, buy a used / refubished Kirby G6 series or up, but not from Kirby directly. Don't call your local Kirby sales company. People hate Kirby because of the often shady salespeople, outdated sales techniques and preying on the elderly. But the machines are made in the USA with a construction quality that is hardly seen any more.
Check Craigslist or eBay in your area. You can get a vacuum that was $1000 new for $200-$300 barely used and they work forever. Bearings, motor brushes, brushrolls and belts are easy to replace. Almost no plastic parts to break. They are bagged, but the HEPA bags are pretty cheap.
Kirby drawbacks are the weight if you need to lug them up stairs, attachments are not on board and the kevlar fans CAN be damaged if you happen to suck up solid, heavy stuff (nuts & bolts, etc) since the vacuumed dirty air passes through the fan before the bag.
Die-soons are made of plastic that becomes more brittle over time and have mediocre suction. It's true that they do not lose suction/airflow, but only have mediocre airflow to begin with! So much power is wasted creating the vortex in the canister that could be applied to pulling dirt from the floor.
If you are okay with some plastic, or want a light vac, check out Riccar. American made and high airflow rates.
http://www.riccar.com/
Regardless of what you buy, when comparing vacs, you should look at air volume in CFM and suction in inches of water column. Don't just compare motor amps!
Dyson: approx 65cfm
Kirby: 115- 125cfm (newer G series)
Riccar: 120-140 cfm
Miele: 140-150cfm
I know quite a bit about air movement because I used to adjust HVAC systems professionally in buildings and have an engineering degree!
Kirby vs Dyson professional test:
http://www.greatvacs.com/KirbyDysonReview.shtml
Good luck!
Daryl
