My experience over the years.

Had a Miele about 30 years ago and it was very good. It died when someone tried to hoover up a spilt glass of water and the motor was going to cost as much as a new cleaner.

We've had a couple of Dysons. They are great; they clean very well, the variety of tools is great, and the connectors for the tubes & tools is easy and very secure. Mine were all mains powered.

Downsides to the Dyson is it needed emptying very often and that could also be quite messy. Possibly a combination being good at sucking up, and a comparatively small hopper/"bag". I stripped it down once as it seemed to be struggling to clean as well, the cyclone/jet engine was full of "dust" and some of it was caked on but after a good clean was as good as new.

Now got a Henry. The bag hardly ever needs changing, the cable is very long, and the tube is long. I don't think it picks up as well as the Dyson and the tools are fiddlier to use as they are all just push fit and also don't feel as good quality.

Yes Henry is very robust, can be easily repaired/maintained, and they just work; that is probably why they are used commercially and so well loved. I don't think it cleans anything like as well as the Dyson though.