I would rate these three as DRV Mobile Suites as the best, Redwood 2nd and Ridgeline 3rd.
But if you are looking at DRV also add Peterson Excel as well as LifeStyle. These three are more on a level playing field.
When you consider Redwood (which is no slouch) there are about a dozen 5th wheels around the same quality. Landmark, Presidential, Trilogy, DRV Tradition, Alpine, plus more.
Not sure if it is fair or not but I do not consider GulfStream as building a quality product. Check out their wiring. Seems haphazardly done.
Agree look at axles (should be a min of 7,000 lbs.) wheels/tires (should be 17.5") frame (should be a min. of 12" I-Beam).
Mobile Suites, Excel, LifeStyle will use a better than 12" I-Beam. These and the Presidential come with 8,000lb axles.
I think 8,000 axles are an option on the Redwood.