I understand what you're asking but I have to answer ti this way. There is no one answer to your question, to find that answer you need statistics and I don't have those.
I will answer you in this manner. I would look at the new and used ones out there. To figure out what I like and dislike before I spent thousands of dollars on a used rv, I would rent different ones for short trips and find out what I liked before I bought.
The other advantage to renting them and trying them is that rv owners you run into all have stories to tell and lots of information on rvs , then i would find a mechanic or two and ask them what to stay away from. The best part of this adventure is that by renting and trying the rv's you learn what you want in an rv, before you get one you may hate. they all drive diffferent too
If you have never bought an rv before I would look at a dealer with a good reputation, I would also see if they give rv owner lessons when you buy. A friend of mine got a 5th wheel and it came with driving lessons and they made sure she knew how to operate her 5th wheel and set it up. They offered free lessons with purchase.
Sorry there is no short and sweet answer... research is called for, I did 6 months research before I got my 1st camper