I've been perfectly satisfied with the build quality of my '98 Coachmen class C. It's not fancy, nor are the finishes or hardware or materials top-of-the-line, but it seems to be decently well designed and properly built, with the electrical and plumbing and whatnot installed neatly and properly. The occasional problem or breakdown I've encountered has not been due to poor manufacture, but rather age and use and somewhat being built to a certain price point.
A lot can happen to a company in nearly 20 years, though, so I'm not sure how useful a data point it may be.
I'm of the opinion that for a used RV the maintenance it received previously is of greater importance than the brand name, speaking generally. A top-tier motorhome that has been neglected is liable to have more serious problems than a carefully maintained low-end unit.