Bit embarrassing 😳 and no, I don’t work for Which? Or Good Housekeeping!
I’ve a Miele (cord/bag less), Sebo (cord/bag), Dyson (cordless), Shark (bag less/cordless) and a G-tech K9 and the handheld one (both cordless/bag less).
Don’t rate Dyson -loses power very quickly- although when working it does pick up well.
Shark one is good, although its selling point was the ‘hair anti-wrap’ thing; my dog is obvs too hairy and I have to cut out the hair after every use.
Sebo is goodish -mine is a bit basic (‘inherited’ from in-laws in order to give to a child when they leave home).
Miele is excellent, although a little heavy and awkward, especially on the stairs.
G-tech K9 initially seemed very basic, but it’s amazing and picks up so much more than the others. I bought it in a deal where I got the handheld as well -you’d need that for the stairs.
All of the above are going strong and are used regularly, but I wouldn’t recommend Dyson at all.
Miele and G-Tech K9 would be top of my list.
(Cleaner also prefers the Miele and G-Tech K9.)
And yes, I’ve quite a large under the stairs cupboard 😆