I am in the market to purchase and install a standby generator for my home. I am considering a generator that will service most of my 3500 sq.ft. home with 2 furnaces and A/C units. I am thinking about a 20kw generator. However, I cannot find any independent reviews that compare the different brands (e.g., Generac vs. Briggs & Straton vs. Kohler) of the same size generators. Do you know of any that exist?