Whether it's our onboard Onan or the Champion 3100 inverter genny we picked up before our first trip out this past Spring, both get whatever gas I use for the rest of our vehicles which is the cheapest I can find using GasBuddy app. On top of that it is normally 85/86 octane where we live and RV due to elevation. Our Champion inverter genny already has run 100 hours unperturbed by cheap gas.
I often hear/read about all the fuel delivery issues generators have with cheap gas, this has not been our experience, our 10 year old Onan has run 1K hours with zero carburetion issues. Don't have any special tricks, just change oil, clean air filter and spark plug annually. Still has original fuel filter. Of course I carry spare fuel filters and spark plugs should I ever need them.
I use Stabil and an occasional bottle of Seafoam on all of our seldom used gasoline motors, have never emptied gas tanks or run carburetors dry when storing for prolonged periods. We have a toyhauler TT and several Honda quads, one is 13 years old and the other two are 10 years old. They start right up every Spring, never serviced by dealer, just same maintenance as genny.