Think about fuel. It takes a lot of fuel to run a big generator for a week or more. Remember that gasoline was difficult to get in many areas. How much fuel do you need to run for a week? How will you store it?
Gasoline goes bad, so you need a plan to rotate your stock (use it in your vehicle, refill the cans).
If you buy a generator that runs on the same fuel you use for heat like Natural Gas, Propane or Diesel, fuel storage is easier. Diesels will run on heating oil. Natural gas sounds ideal, but it may be shut off in a disaster.
My 2000 watt Honda EU2000i will not run everything in my house at once, but kept us comfortable for 10 days. It ran 233 hours and burned 19.5 gallons of gasoline in that time, only 2 gallons a day. I have enough gas cans to store 20 gallons, it was just enough for this event.
My friends and neighbors with larger generators (5KW plus) generators burned 5, 7 or even 10 gallons a day.
My next door neighbor runs his 5KW generator on propane drawn from the same big tank he uses for heat, hot water, cooking, etc. He had plenty of fuel for the 10 days we were without power.
If I get a larger generator, it will be a Diesel. I heat my home with oil, so my heating oil tank would supply the generator.