[vreihen16]

If you have natural gas available and are willing to accept that a major regional disaster like an earthquake could disrupt the gas flow and leave you in the dark, it is a great option.

Gasoline works for short outages, but a typical 6.5kw portable generator will suck down 10+ gallons/day...and you need a gas station that's open and has power to refill your cans. Plus, the ethanol used in most pump gas doesn't store well for more than a month or so, meaning that you'll find your stockpile of generator gas stale and gumming up the carburetor/tank when you try to fire up the generator in the dark.

I have no experience with propane burn rates, other than to say that you need to have a steady delivery of portable tanks or delivery trucks to refill a larger tank. At least the carburetor doesn't gum!

I have seen dual-fuel portable generators, that will run on a BBQ propane tank or gasoline. No idea how long they run on a BBQ tank, but probably less time than a tank of gasoline.

I'm surprised that you don't have diesel on your list. If I ever upgrade my portable gasoline generators (yes, more than one), I would go with a Cummins Onan stationary or RV diesel generator. Why? Because I have oil heat and a large tank of heating oil, and am pretty sure that I can plumb a diesel into the heating oil tank and run it for days between deliveries.

Whatever you do, make sure that it is wired per electrical code using a proper transfer switch, and run it outdoors to prevent carbon monoxide poisoning.....