Having stormed through a quick succession of 4 vacuum cleaners in as many years, I asked a friend (who also happened to be a cleaner) what she used at home.
Well, it was like opening the floodgates. After running through what she categorised as rubbish (3 models of which I'd previously owned) she said that any self-respecting cleaner could only recommend the Henry Numatic.
She'd had hers for about 6 years and it was still going strong. She used it both bagless and with the Numatic bags (which she bought on ebay!).

-Dimensions-
This particular model's number is HRV200-22.
It weighs 6.6kg (and is not difficult to lug up and down stairs)
Dimensions are: 340 x 340 x 370mm but as it's a barrel shape it won't sit on a stair whilst you vacuum around it unless you balance it on the step above and wedge it with your leg. If you have a turn in your stairs, that works well.
The cord is long enough (at 10 metres) to start hovering upstairs if you plug into a socket on your landing, work your way downstairs and carry on for most of the house before having to unplug it! Numatic claim the cleaning range is 31.8m and I'd say that's pretty accurate!
The hose is 2.4 metres long.
It has a pretty powerful 1200w motor. It's not hugely noisy either.
It holds a fair bit of muck too between empties with a 9-litre capacity.
And comes with the manufacturer's 2-year warranty.

-Quality-
Excellent for pet hair, shedding rugs (and boy have we got one of those), good up to edges (which was a big bug-bear of mine with the Dyson), the main brush has a foot operated "switch" of sorts which raises a set of brushes which give the carpet a good brush and pulls out hair and lint which get stuck to the pile - it's essentially for long or short carpets, but it's a good restorer for carpets that are a bit "flat" too.
It's also great on wooden or laminate floors. I have a wood floor in my kitchen and laminate in our family room and it is perfectly happy picking up bits and pieces, food - even dried out pasta (shame on me!) or dead leaves from one of our houseplants is not a problem.
The filter is not quite as good as the Dyson, but it's not far off, there's no dust blow-back like you see on some and it's at least half the price of the basic Dyson.
It comes with a small set of cleaning heads.

-Cost-
We bought ours on-line from Argos for £89 (my model is currently on there for £93.87) - and that was just over a year ago. And having had a trawl around t'internet, prices seem to have remained the same. The best deal I could find today was with www.cleanstore.co.uk £88.95 with 5 free bags and free delivery. Even Amazon marketplace does them now (£88.90).
Vacuum cleaner bags (which I buy on ebay - although we're only on our 3rd bag!) are £3.50 + p&p for a pack of 10 - usually around £5.99.
I also managed to source the flexible hose which managed to get broken when poor old Henry was unceremoniously shoved under the stairs. Again, ebay - £7.50 + p&p.

There are other Numatic models including a wet and dry version, and "extra" version, a turbo version, one with an Airo pet hair brush option, a total all-in-one with carpet cleaning….they even have different names - there's George, James, Charles and now even a Hetty!
Numatic has a great website where you can meet the family and see which one might suit your lifestyle!
http://www.numatic.co.uk/ (go to the Home option on the right of the screen).