For us it was two big things:
1. The extra dedicated sleeping space for DS (although some A's have the drop-down bed, but that's one more thing to mess with and set up)
2. The straightforward Ford chassis that is used on a zillion delivery trucks and ambulances across the country and could be repaired in just about any small town. Since we have work and school schedules to contend with, our vacation time is at a premium so a tow to the nearest place that can handle a big class A chassis is just too time consuming for us. Once we're retired and have plenty of time, this won't be as big a deal.