I don't find a huge difference.
We currently have an Electrolux. I had a Dyson for 15 years and it did very well for most of that time. Towards the end of it things were starting to wear out and I couldn't get parts any more. It still worked, just not as well.
I also have a sub-$100 shop vac paired to a cyclonic separator I made out of a 5-gallon bucket. The separator shakes out most of the bigger stuff it sucks up, meaning I don't have to change the bag as often. It's more cumbersome to carry around because I never got around to building a single base for it, but works pretty well on hard floors. For carpet or rugs I'd go for the Electrolux or the Dyson, because they had brush bars that helped agitate the fibers and get the crud out.