I think that all the engines used today are pretty good. The Tecumseh L-Head engines have been used for years, and seem to last. The Briggs OHV engines are reportedly a little quieter, and are also very good.
The main thing is to buy a quality brand, like Simplicity, Toro, or Ariens. (in that order, IMO) They all have good warranties, and use top-quality components. Either of those three brands should give you many years of reliable service.
1995 Simplicity Sno-Away 860 Snowblower, 2001 Craftsman POS lawnmower