I did an exhaustive amount of research on 5vers back in the 2003-2004 timeframe.
After I was able to get up and about, I haunted the local RV dealers and looked over every brand I could with a fine-toothed comb. One of the first things I noticed was that about 80% of the units out there are almost completely generic except for decals and how the interior was arranged. Particle board construction, flimsy staples, ridiculously cheap hardware, sloppy sealing and wiring. Out of those construction features, careful attention to sealing the seams and window / vent penetrations etc is the one that makes the biggest difference to the end user. If you have a leak, it is never good... but when your particle board begins to dissolve you are really screwed

"Get the Sawzall, STAT!"
The best value for the buck that I found, with the most consistent construction quality, was the Arctic Fox line. Very impressive for the price. I came very close to buying one, but opted out after my 5ver / truck camper decision fell on the side of truck camper. For my purposes, I think I bought the best possible unit, but if I had bought the 5ver it would have been Arctic Fox.
If you do a search, in the earlier days of the TDR forum one of our forum members did some mods on his Arctic Fox and made some very good posts that show how they were constructed.
Two interesting points about the Arctic Fox, and RV's in general. All of the Arctic Fox units were once made at a single plant, but a few years ago they opened up a plant back east if I recall correctly. The reason that is interesting is that back in Indiana where a lot of RVs are made, the manufacturers are fairly close together and "share" a lot of the same workforce. I was told by multiple folks who have been involved in delivering rigs etc that quality has gone down a good bit at the more generic RV mfgs because they had gotten into the habit of using a lot of illegal alien labor. Guy X gets fired for incompetence at RV Company A, walks down the road to RV Company B, and continues his same sloppy work.
Accordingly, be very careful about assuming all rigs from manufacturer X are equally well built. From my direct inspection of new units, they can vary wildly even between "identical" units. Take the time to look 'em over closely before you buy - look in every nook and cranny. A good used unit is a far, FAR better deal than a shoddily built new one.
Also, count me in the "Didn't think I needed a generator but boy I love mine" group.