As an update, I flew JL F ORD-NRT-CGK in mid-April and just stepped off of NH F NRT-IAD today.
Overall, I still think JL F is the better product. The lounge for JL F is better (discovered the sushi bar this time around), the onboard catering is better and higher quality (the Western and Japanese options this time were outstanding), and the service on both segments were fantastic with a great, proactive crew who were friendly and interactive.
Contrast to NH F, where I found the food merely "decent" this time, and I find the cubicle design a bit cramped. Crew was great, but was reserved compared to JL. The ground service was somewhat of a disaster - having arrived at NRT at 6:20 coming off a TG flight, there was no NH staff anywhere to be found to print off my boarding pass. They couldn't do it at the lounge either and I eventually had to wait for the concierge who showed up at 9:30 to get my boarding pass (I was starting to get worried something went awry with my booking as the other agents couldn't check me in.) Eventually all was good, and they retagged my bag for my connecting flight to YYZ (the TG agent couldn't see the last segment and I gave up fighting.)
One big brownie point I'll give to NH is for their cabin temperature. The cabin was noticeably cooler than JL - which I found "hot" at times and was sweating despite only wearing a t-shirt and shorts. In a full cabin on ORD-NRT, that wasn't so easily fixed. But when my NRT-CGK flight only had 2 passengers, no problem asking to dial the temperature back down a bit.