The smaller 1000/2000 type of portable generator will be much quieter than the all purpose type on wheels that are usually used where noise is not important, like on a construction site or for emergency use.
The easiest to get serviced anywhere in the USA are the ones from Yamaha.
My generator is a pair of solar panels that are unbelievably quiet. I often forget that they are sitting on the roof generating power day in and day out. Nothing to start and stop and nothing to refuel or repair.
I seldom use the AC as the advantage of having an RV is being able to move it to where the weather is better.