When I moved house, I was in a position where I needed a new vacuum cleaner. I had a cordless Dyson. It was very clever, light and swishy. But, it broke - a key piece of plastic snapped in a way that was entirely impossible to fix without buying a new machine. After considerable research, I came to an odd conclusion. Despite the fact this little fella contains a heck of a lot of plastic, he's a lot more sustainable than many others on the market.
These vacuums are known to last forever. The only people I've known that get rid of their Henry (or, in my case, Harry) are because they've wanted to "upgrade" to something new. Not because it's broken. You can get almost every part that could break as a spare. They are from an era where there was an appliance repair store on your high street that was capable of repairing most appliances.
But yes, they do use bags! Oh no! But actually, if that extends the life of the motor (by acting as a filter), and is one less mechanism to fail (like the bin latch on my old Dyson) then is that really worse? It might be a consumable product, but so are binbags and we seem to cope OK with those...
tl;dr: a basic, repairable piece of tech to perform a basic task proves to be generally better than a very clever but fragile one.
Energy efficiency is not an easy thing to calculate with a vacuum cleaner - as so much of the "efficiency" is down to how you use them. But I *can* tell you what's not
efficient - vacuuming half your house then having to put the thing on charge for an hour then finishing it off later!