It looks like the second snowblower there is just a slightly larger version of the first one. They use the same mechanism, and I'd bet that the larger one is only slightly more powerful. They both suck, most likely.
Gotta go with the big, all metal, stamped steel frame guys with a big Briggs & stratton or dual shaft tecumseh on it. At least 5 or 8 hp, and self driven, too. (If anyone has a dead snowblower of the above description, I'd take it off your hands!)
The plastic wrapped snowblowers they're making these days are no more powerful than my "Ol' Flappy" Toro S-200 that my family has kept alive for 3 generations. Cheap snowblowers earn more money than well built ones because as long as they look fancy people will pay about as much for them. Most people don't bother to fix the darn things when the plugs foul after a few years, so it's back to sears for another beater.
Here's some snowblower history!