Our RVs have always been chosen based upon the floorplan. Which floorplan best fits our needs.
We look for floorplans where there are no bottleneck areas- for example if someone is washing dishes do they have to move out of the way for someone else to get by.
We ask ourselves if we were on a trip and the weather is so bad we have to stay inside the RV for several days or a week will cabin fever kick in. Is there spaces where she can go (dining area) and do her thing and I can go and do my thing (Living room recliner) so we don't end up killing each other.
I also look at the outside to determine storage, ease of dumping, utility hook up, ground clearance...etc.
Like others have said most RVs are reliable and will stay together for many years of use as long as they are proper maintained and not abused.