You will no doubt receive many and varied opinions on your post. If your RV lifestyle will involve logging high mileage on a coach, perhaps a diesel powered unit would be the best choice.
In our case we opted for a gas powered coach as we wouldn't be logging high mileage. Our travels average 5-6k miles annually spending 3+ months at any one location.
Insofar as we would be living in the coach more than traveling in it, we gave priority to a coach with a comfortable, livable floor plan that would best suit our needs.
Fortunately we found one in our 2000 gas powered coach we currently own which is now almost 17 years old with 91k miles and still in great shape.
Wishing you the best on your choice of a coach, and may you enjoy many fun, safe and trouble free journeys.