First a definition - to me whole house means that I can operate off the generator just as though I was still on the grid.
We moved to the Smokies - 30 miles west of Asheville- from Miami. There I had a 15 KW gas powered Generac with manual transfer switch. When I moved here the deciding factor was - cold weather- I did not want to have to go out in 20 degree weather with snow on the ground to start a generator. I have a 350 gal propane tank buried under the rose garden in front of the house and the only thing in the house that uses it is a small backup furnace. So I had a 20 KW Generac with automatic transfer switch installed. Total cost including having the gas company run a line from the tank to the generator was $9,000. The generator has a weekly exercise / test / battery charge cycle, starts up and runs for 12 minutes to do whatever it is that it does. Power goes out - generator comes on in 20 seconds. Power comes back on generator goes off and you don't even know when that happens unless you are close enough to the generator to hear it shut down.
Best $9,000 I ever spent.