Having lived through Hurricane Sandy in NYC: don't assume you can get gas to fill your generator in a disaster situation. Solar panels paired with a battery aren't dependent on a supply chain (that itself needs energy).

Yes, getting energy from a sustainable source of energy is the best way, but assuming you only use it for power outages once or twice a year, I am not sure it is worth the investment. Especially if you expect it to last a day/few days (if you are self sufficient for a few days you'd better do it all year long).

I agree, but I guess that the generator have a no zero starting time. (Do you have o turn it on manually?) So the battery keeps the electricity for the meanwhile.

Also, the generators are noisier. Perhaps you can turn them off during the night and use only the battery while you are sleeping and the electricity consumption is smaller.

And is a fraction of the cost, best case, or about the same if you want one capable of powering your entire household load indefinitely. And if you have natural gas service, you don't need to refuel either.