Should you choose a gas or a diesel powered RV? The answer to that really depends on what you expect to do with your RV and where you want to go.
Do you plan to take you RV out for occasional weekend trips? Do you plan on sticking to the roads and standard RV parks along the way? Have no need to tow an extra recreational vehicle behind your RV? Then a gasoline powered RV probably best fits your needs.
Do you plan to RV full time? Then you're going to wind up storing more supplies, adding weight to your RV frame. The frame and axil ratings on a diesel RV are much heavier than a gas powered RV, so they can bear considerably more weight. The diesel RV frame gives you more durability, making off road RVing a better possibility if you like to rough it a little.
It follows that with a stronger frame and axils, a diesel RV also has more strength to tow extra two wheel vehicles behind it. Gas powered RV's are limited in this capacity.
Environmental concerns may also weigh in your choice. While not as strong, gas powered RV engines burn cleaner than diesel fueled engines. Something to consider.
Should you choose a gas or diesel powered RV? There are advantages and disadvantages to both types of RV's, so choose based on your needs and expectations.