Being a smaller outfit - I'm not tied to any manufacturer in particular, lets me bounce around between suppliers - source the best product for the application.
For 90% of your typical doors - usually putting people into the R9 thermatech:
http://northwestdoor.com/assets/broc...e_20121005.pdf
Main reason, good quality 'builder grade' door face - and an unbeatable hardware package that comes with it, complete with 10 ball bearing nylon rollers, good steel vinyl weatherstrip, real 14ga hinges.
Generally when we're going up in insulation - move to the upwardor milltown collection. More cost effective than the northwest.
Can also deal in Wayne Dalton, Garaga, Richard Wilcox, Amarr, Steel-craft, Martin, and a couple others - usually it's specific needs/looks...