Haven't flown it personally, and someone with more NH knowledge could probably tell which a/c is likely to be on the route. But from SeatGuru it looks like NH's Premium Economy seat on the 77Ws is wider by almost 3" compared to regular Y, plus more legroom. SG shows 3 versions of the 77W, one of which has 31" pitch in Y and the others 34".

For their 772, looks like you'd gain 2" in width and quite a bit of legroom over the 31-32" pitch in Y.

NH regular Y widths will are narrow, their Premium Y will be closer to, or exceed, DL/UA (depends on which DL/UA aircraft). But Premium Economy on NH is a separate class of service, whereas on DL/UA their Y+ is the exact same seat, just increased pitch. NH Premium Y is a better seat - looks like they have leg and footrests. I believe the meal is service is supposed to be improved compared to Y. Also departure lounge access in NRT is included.

So I guess it depends on your preferences and comfort level desires, compared to what you're willing to spend. Personally, if the cost wasn't an issue I'd give NH Premium Economy a shot.