I love my Oreck... sorry to go against the obvious Dyson Love, but I've been very happy with Oreck. My father had his for 12 years and I only had to replace it after it was abused by a restaurant I worked for. I've bought a second one, it does great on rugs and hardwoods floors - has two settings, plus the free canister and car vacs make all vacuuming a cinch. So, for value and quality, I love my Oreck - though I did consider the Dyson. And for the record, I have two cats, but no carpet, just rugs.
And something else I don't think has been mentioned is whether you want a bag or bagless... but I prefer bags, having had bagless and always finding it a messy pain to empty.