My experience follows:
I have two generators. Two is one, one is none. One propane, one gasoline.
Longest we've been without power is 60 hours. That won't impress folks in the hurricane zone, but around here, SE PA, that's worse than many.
One generator is a GENERAC on propane, 500 gallon buried tank. Wisht I had gone 1,000 gallon, but haven't needed even the 500. Just wished I had gone bigger.
Edited to add: consider buying your own propane tank. YOU control who you can buy propane from. Otherwise, propane is locked in to the one company that supplied your tank.
Reduce electrical loads, if you can. I mean long term; have a electric water heater? Go natural gas or propane. Other big electrical loads? Have a backup that is non-electric, if possible. Lord help you if your house is all-electric.
If you go GENERAC whole house, get the automatic switch set up that does your whole breaker panel, not just select breakers.
Cheers!
Ray