Welcome to the forum Richard. Not sure what you are asking but assuming you want to know if a generator that runs on propane or gas is best. If so I prefer the gas. Are you talking MH or TT? If TT I might opt for propane. Need more info on what you are wanting.
In case you're still interested, there's a list of best generators of 2019: https://lawngardentop.com/best-power-generator. These are the best options for RV among inverter generators. Back on topic: some inverter generators, by the way, run on gas too. We need more details in order to help you.