I have a Dyson. It's really quite terrible with weak suction. I got it free from my sister-in-law when it "broke". It took me an hour to disassemble it and clear out all the clogged sections. In order to keep it working it needs a full disassemble and cleaning around once a year. It's an excellent example of a shitty design.

My other vacuum is one I got 18 years ago that still works well. The brand has since gone to shit so I can't recommend them now.

What to look for:

First look at the amps on the bottom. Amps = suction power. The more amps it draws the stronger the motor is.

Second you want a beater bar. This is the belt driven part that spins. This makes the vacuum much more effective on carpet. It gets pet hair a lot better.

Third you want something with common easily replaced air filters. These clog easily and need to be replaced constantly. Look for machines with oversized filters.

And last, look for something simple to break apart and fix that you can find affordable replacement parts for online. Fixing a broken vacuum is generally pretty simple.

These are generally midrange machines not the cheapest but not the most expensive. In the long-term these tend to be the most economical in terms of performance/cost.