I know of no such airline. Now if you are enquiring about QANTAS, I'd take it for First or Business, but go for UA if you can get a seat in their Y+. If you can't get Y+ on UA, then go for QF in ordinary WHY. You get seat-back videos whereas UA only have their old crappy projection screen.

Meals in WHY are both as good (or bad) as each other - but I'm thinking UA may be a touch better in some ways.

If FF points are important, the UA program is heaps better for redemptions (generally), but the QF program makes it easy to earn good points on short flights in Oz.

Is it just my imagingation, but isn't FT full of "comparison" threads at the moment (eg UA v/s QF or QF v/s CX etc)?