You will get a million views on this topic. Rather than give you a recommendation for specific brand, I'll provide you with some points on what to look for when comparing machines.
Engine: B&S in preference to Tecumseh but either in preference to Troybuilt's - Soybuilt. They're using Chinese engines now.
Chassis: The thicker the steel the better. I usually look at the sides of the intake housing. I push in/out on the sides to see how much they bend. The stiffer the better.
Look for bearings instead of bushings. If nothing but bushings in your price range, look for bronze or metal bushings in preference to plastic.
Controls should be well designed, simple and robust. Avoid electric and cables as much as possible.
Auger gear case will in all likelihood will be aluminum. Choose the largest size available in the price range. Larger gear cases usually mean larger stronger gears.
I prefer steel chutes & deflectors. Plastic calls for less maintenance (painting) but can weaken in areas where holes are drilled for fasteners to mount them etc.
Fit & Finish: Make sure the machine is assembled properly. Look for loose/missing fasteners, improperly or misaligned parts. If it's shabby on the showroom floor, imagine it after a few years of hard service.
Service: If you don't do your own work, make sure you buy from a dealer rather than a box store. You might pay a few bucks more at a dealer but that will pay for prompt and competent service if required.
Warranty: The longest and most comprehensive of course.
