I live off grid and run, almost, everything on solar, I do use the generator for the welder and I will use one of the small generators for saws and stuff in the winter. I have a 10k propane generator I would have to look but I think is a generic or onan. It's 10 or so years old it probably runs 10 hours a week in January but that is so weather dependent, it needs to be cloudy 2 days to need it.
My house, 2 storys 28x28, runs very well on 6000watts of inverter power. I have 220 deep well pump, microwave, 4 big TVs, Starlink, 3 refrigerators and an tiny house for my parents. I can easily run the house with my 6000 or 6500 Yamaha and still charge my batteries backup.
My old house in Vermont, were in Arizona now, was 5500 square feet with 10 adults living there, I had a 6 braker generator isolator panel, I higly recomed using one it's much easier than words, I did that for years. I ran all the neaded stuff with the Yamaha.
So I find it doubtful that you need a bigger one than I have unless your heat requires it. As to propane v gas unless you are willing to refresh your stored gas every 2 months propane is a lot easier. Mine has taken to starting very hard but it always started easy until recently. The one problem I do have, and it would be the same for any standby generator I think, is keeping the battery charged, as it has a 110 charger and I try not to use it, I have a solar panel on it and I have been very suprised how much the elctronics draw.