I highly recommend going to a vacuum store and talking to the owner to get their recommendations. I've heard a lot about Dysons, but when I talked to a vacuum store owner, she couldn't have been more negative about them. She said they were worth about $80, and that as much as they said they had great suction, their suction was rather poor (about a 33 out of 100 on the suction scale, if I remember correctly). She also said that even if you need a simple belt replaced, which you should be able to do yourself for $2, you send a Dyson in and get charged $80. Eeek! She also said that Dysons are currently being sued for false advertising. Apparently, the maker of Dysons used to make another vacuum (Phantom, not sure of the spelling), and they were sued as well, so they stopped making Phantoms and started Dysons. Finally, she said that bagless vacuums are a bad idea for homes with small children, because they spew bacteria whereas a bagged vacuum catches it and keeps it in the bag.
She wasn't as vocal about Orecks, but did say she didn't recommend them. Her recommendation was Sibo, a European company. The vacuums looked pretty nice and had lots of great features, and while they were a little pricier than a Dyson, they're meant to last a long, long time - like 20 years as opposed to a Dyson's 5.