If money is no object and you can secure seats your happy with on NH113, I'd take that option. The longer TPAC flight is nicer (plus avoiding the long domestic segment), Polaris Lounge at IAH will be nicer than JL J lounge options at LAX, assuming you don't have OWE status. It is harder to assess whether $2.5k is worth it as valuations are personal.

JL and NH both post menus online so you can get a feel for their F&B offerings.

I personally aim for 4-5h of sleep on flights with that arrival time. I am still plenty tired to sleep on arrival in Japan and get over jet lag relatively quickly.

If this is your first time in Japan I think it's nicer to start in Tokyo (purely my subjective opinion.) If you need to get from Osaka to HND on arrival or departure I think the domestic flight is easier than the shinkansen (that's another debatable opinion), and you'll still have opportunities to take the shinkansen at some point in your trip.