New Horizon is the best made rig on the market. Very little flash (things like stained glass inserts in the cabinets, etc they don't do those things), just solid construction. But in your size range this could run $100K and probably would require an F450 or larger.
Excel by Peterson Industries and Mobile Suites are right up there also.
Again these are heavy and would require a serious tow vehicle.
A gross estimate of longevity can be had by weight, ie heavier rig is more likely to last longer.
IMO Fox Mountain trailers, despite being reasonable well made do NOT have the storage a full-timer needs. Their storage is set more to the vacation level