Dyson

Shark. I have a shit ton of carpet amd stairs and it's fabulous.

I have the Shark Powered Lift Away and the Dyson DC65 ball upright and I definitely prefer the Shark over the Dyson. Though I did go to Strosniders a couple weeks ago and bought an entry level Miele C1 Compact canister on closeout for $199 and it does a beautiful job on my wood floors and furniture. It doesn't have a powerhead so it's pretty useless on carpeting/rugs but absolutely great for hard surfaces.

Got a Shark at BJ's for ~$220 that is f'in marvelous!
Powerful, light, yanks itself over the carpet.
Makes me want to vacuum everyday...well maybe not quite. But it's sweet.

I have the costco version of the dyson ball and I LOVE it. It's about 10 years old and going strong. I own a lightweight shark that I got at bed bath and beyond. It's good for the kitchen floor (although never picks up everything). I cannot compare to a lightweight dyson as I have never used one. Quite honestly, I wish I could find an old fashioned electric broom with cord that my parents used to use. Those picked up everything and did it well. I have yet to find something lightweight that actually does a really good job.

My Shark Navigator has an on switch that goes from off to either a carpet setting or a bare floor setting. Very easy to use.

Neither.

Dyson is going strong after 7 years. Heavy though.