I look at RVing backwards from most people because for me it's not "pick a floor plan you like first". First and foremost is the platform. It's a motor vehicle and I have to like driving it. I've driven gas coaches and I didn't like driving them.
It's the same reason I didn't like pulling our travel trailer with our gas pickup. The gas engine just has to rev too high in too many situations and doesn't produce the torque of a diesel engine. Not only did the engine scream going up hills, we slowed down to 45 doing it. Pulling with a diesel engine is just better in my opinion.
If you're looking at a smaller motor home I guess a gas engine might be adequate, but I'd think a diesel would be a better choice for anything over about 34 feet.
We don't want to spend a fortune on a motor home, gas or diesel. We decided to move back a few years and get an older, quality diesel pusher instead of a newer gas coach. A diesel is more expensive to maintain and repair, but the odds are you won't have a lot of repairs for either one if you buy carefully.