If you fly 50K miles a year, you could get 3 one way upgrades on certain fare class tickets with ANA. Same I think for JAL. You'd get a pat on the back from UA and SQ (maybe).

But, you can also credit any SQ or UA flights to ANA. Miles on ANA will expire of you do not make top tier while UA's don't. ANA has a family sharing account.

If you went with UA you'd get double miles on all flights (NYC, Japan, Europe)if you hit 50K but no upgrades certificates. You need to consider that if the upgrades clear on UA (H class required) it will cost you 90K miles jut to break even up the 3 upgrades you gave up by not choosing ANA. Of course if you in turn applied those 90K (if earned on ANA) to ANA upgrades, you'd be in business every flight to Japan assuming you clear.

Also to consider. If you buy less than a full Y it's only 70% base mileage credit.

Lots to consider.