At first I wanted to respond to your comment about NH "whining" about changing dates after departure. There would be no whining. Rules are rules and you couldn't change your dates!

However, I believe now you meant "win."
NH will of course take service and likely entertainment.
I've always liked the UA C seats. The 777-300 will have Newstyle which is a nice seat too, however the inclined "flat" seat is more marketing than functional. You will slide unles you wear your velcro pants!

Shorter flights? I'm sure you bean better connections. On an award flight (non-earning), when considering these two products, I would build the "shortest" confirmable routing If my dates were set and there was no changes. If changes were a possiblity, stick with UA if you can get confirmed in C.

Scho