Aside from narrowbody vs. widebody are there appreciable differences for one in Business class between these 2 planes? For such a short flight, I'm thinking it may not really matter. The 767 flight however, would give me 5 hours in NRT for lounge experiences, compared to the just over 2 hours if I took the later 737 flight.
I believe on the 737 flight, you get to experience one of the oldest "vintage" Business Class seats in the region, with monitors barely visible that you will just close your eyes and get a good rest. It will probably also be quieter as most others would choose the 767 flight.