They are all commercial units and work very well, like a Hoover on steroids but are not cheap. Make sure you can remove and attach the bag easily. If you are not mechanically inclined, buy from a service dealer who can properly assemble and set the the unit up.

I've been using a Billy Goat KD512SP for about 5 or 6 years now. It makes quick work of my 1.1 acre yard cleanup for the most part. For someone with a relatively flat yard, I think it would be ideal. I have a very uneven, hilly yard, so it makes it more of a challenge - the front end tends to dig in when set low to the ground. The self-propel comes in handy on the uphill parts. It can get a bit cumbersome when it's fully loaded. Very noisy, very dusty to operate. The B&S Quantum has been good to me, although it can be a bear to crank over on cold days. Nothing a little spritz of starting fluid can't handle though.
It was an expensive unit, around $1000 at the time, but well worth it IMO. I've never used the Craftsman model, but from what others have mentioned, for larger yards, the BG, DR, Little Wonder seem to be more capable.
Good luck!

Abelman, I've had a Craftsman for about 18 months, and it does a good job. I'd suggest you try three things. 1. Make sure the lever on the front of the unit is set properly; I find the diagram confusing, and sometimes set it wrong. 2. Check that the hose is set in the upper position. 3. Try going slower; if leaves are really deep, even the slow speed on the self-propelled unit can be a little fast. My biggest problem is that the corrugated hose catches twigs and causes jams; I think a smooth hose would work much better. (BTW, I've got over 50 blackjack and post oaks, plus a few elms, a large mesquite, and a bunch of deciduous shrubs, so my unit is handling lots of leaves.)