I think it comes down to the amount of usage, and availability of non-ethanol. If you use the generator enough the cost is a concern, you go through the gas quick enough to not be a problem. If the fuel will sit for 2-3 months I'd run non-ethanol if available. If not available I'd use a stabilizer.
I'm lucky that non-ethanol is easy to find around here. I run it in my boat and lawn equipment. It may add $150-200 (boat) a year to my fuel bill, but if it saves a carb getting clogged on my 2stroke outboard and burning the engine up it will more than pay for the added fuel costs.