In my industry we had maybe 500 Onan generators and they proved to be a workhorse and very reliable. They need to be run and run a lot.
Replacing with portables seems to be a costly solution to a small problem. Storing them, carrying fuel....no thanks.....
Servicing your unit then using it like it was designed to do may be the best option for both ease of use and dollars spent.
Portable units. Always turn the fuel supply off and let the unit run out of fuel. This will prevent fuel from gumming up in the carburetor.
I have a 10 year old Champion that has seen plenty of abuse. It sits sometimes for months and once i turn on the fuel, wait a minute, half choke and half
a pull it starts right up. i started using non-ethanol gas in my saw and rototiller. I still include fuel treatment though.