I think the OP had the right idea to ask here about a comparison between NL's and BF's construction strength, quality, etc. Because the quality and durability of those brands of trailers will carry over to their truck campers (TCs).
Unfortunately (and what the OP probably could not know), there were very few NL trailers built and I don't know if we have more than one or two NL trailer owners as members here. So the data set is might small for that brand. Bigfoot
owners we have, but not NL owners.
I've not run across any disgruntled BF owners around FGRV. There have been a couple of threads about owners needing to strip out wood around their vent opening to rebuild that area, due to a leak around the vent; but that is possible with any roof vent and is mostly preventable with maintenance. And I also frequent Woodalls/RV.net forum, which has a bunch of NL TC owners; again, I've not heard any complaints from them about their units.
I hope that helps.