Even the so-called high end units and those brands mentioned in your OP have their share of problems. When we purchased our current rig a decade ago the factory could not keep up with orders and opened additional production facilities to keep up, no different than today with RVs selling like hotcakes. I'm handy and prefer to work on our rig personally, under warranty dealer had no problem providing parts.
Most issues were small and easily remedied, added many modifications along the way and it still is providing us lots of RVing fun although we are currently searching for a floorplan that is better suited for couples and extended living. Grand Design is on our shortlist as are others, have no qualms on purchasing our next rig knowing I will only purchase from a dealer that is willing to go the extra mile to make it right.