Being a Northwood owner and reader of the Northwoods Owners Forum what I've found out is that NW in general builds a heavier more solid trailer than most in the same class. They're pretty basic in their functions. Grand Design uses a more complicated city/fresh water setup with multiple valves that can get tricky to use when certain tasks are needed. NW uses a simple fresh water gravity fill port located on the outside of the trailer. Simple dump valves. Superior roof framing with a continuous 5" of insulation. Not 5" in the center tapering to near zero at the outer edges.
NW is not with out problems though. Owners report a shower leak in many 27-5L showers. Easy fix and most know about it before purchase. Others report some sloppy quality issues like stripped screws, and such. But what you won't see very often like you do in most Elkhart brands is things like slides that don't open or close right, furnaces that don't work properly form a design standpoint. One brand I've read about has the furnace located in a hutch base behind a cabinet door. Owners complain of excessive heat in the hitch.
NW builds a simple no frills RV that is IMO more user friendly and geared more towards the dry camping aspect. ORV follows the same mold and IMO does it a little better with nicer amenities, better floor plans and nicer looking interiors. NW uses the KISS ideology. Less to go wrong and when you don't have to take your trailer in for repairs you're happier.
Grand Design knew all to well when the company was formed that it's impossible to build a trouble free RV. So instead of reinventing the trailer they decided to offer better customer service. That way buyers will be happy when they are getting it repaired. That seems to be working as GD has grown into the 3rd largest MFG IIRC. Kudos to them. But I'll take simplicity over gadgetry.
In the end though many buyers own brands from all MFG's and many have zero problems in their usage. You do hardly ever hear about really disgruntled NW-ORV owners.