I think you should first decide where you want to go in your RV and how you want to use it. We went full time and then bought a small place in La Paz. We park our RV at our house here and continue to use it but integrate it with our home. Then, we travel throughout the US during the summer months in our 5th wheel.
So our specifications for an RV were based on the fact that we wanted something sturdy, but not necessarily new and something we could travel safely on mountain and narrow roads - especially where we go in Mexico. We also didn't want something too big because it limits the parks we can go to and the places we can boondock.
So first think about where you want to go and what you want to do. That will dictate size, new or used, floor plan, whether you need some extra money for solar (if you want to boondock), etc.
Do you also want to be able to haul bicycles, kayaks, or some other small toys? What hobbies will you engage in after your go full-timing that might dictate size, construction, extras, etc.
Good luck!
