Hi, (this is my first post, please forgive any etiquette transgressions)

I'm planning to travel to Japan (either NRT or HND) on 8/20 or thereabouts. I can fly either ANA or Delta.

I'm Platinum Medallion on Delta and Premier Platinum on United. Which airline is more likely to give me the all-important upgrade? I can be flexible on dates, +/- a day or two, and I don't really care about time.

Am I better off booking on Delta because I'm Plat. Medallion, or is ANA a better choice even though I'm in United's program?

(I should mention that I'm Plat in both of these programs as part of a status matching program via my company, so I don't have a ton of miles/points to use).

Second question - If I don't get either upgrade, does anyone have a recommendation of which coach/economy class is better?

Thanks!