Brand recommendations

At that age I would worry less about brand and more about a specific unit's shape. Unless you are looking at Prevost, foretravel or some other high end brand - which does not calculate into your budget- brand won't mean much on units that old. The reason is there isn't a ton of difference in production level quality to start with. Most carry the same chassis and components so what quality you may have had at assembly has been shaken, rattled and rolled down to an even playing field. What you want is a unit that that is well cared for, never had a leak and is mechanically sound. Add to that newer components if the buyer has installed them. Tires is a biggie. A 20 year old MH will have a lot of stuff that is either in disrepair, needs replaced, is outdated or all of the above. Some tout different brands have different quality, but a 20 year MH from a "better" brand could be in far worse shape than one of a perceived lesser quality that was cared for. It's a bit like asking if a 20 year old Chevy is better than a 20 year old Ford. At that age too many other factors supersede brand and what may be true now certainly wasn't true 10 or 20 years ago. Just find a unit in nice shape and forget about brand. In a newer unit it may make more sense but not on a used on that old. I may get some flak for this post as it's my opinion only and brand can be a heated topic around here.

On edit: Another consideration, probably one of the biggest is floorplan. A nice, well cared for motorhome that is a screaming deal won't mean a thing if the floorplan does not work for you, especially full timing. You need to decide what you want and need in a MH, and THEN look for models in good shape and good quality. You will be living in it, so the floorplan is critical.