Re Alliances there is no way apples = apples with 3 cabin long haul aircraft OR lounges.
Sad to say United Bus. on 747 (except for exit row upstairs IMHO) compared to same with Thai or Singapore Air are in a different league entirely. And SO are the business lounges in all 3 cases.
I flew UA SYD-LAX a few weeks ago in a center row C seat and the crew and seat and "feeling" retained form the flight was very disappointing. In coach on Thai or SQ I've always got better service than on that flight. And usually nicer wines even - mad but true.
Others may differ but my take is that comparing ANY major USA airline with ANY major Asian airline on same seat class will yield similar commentary.
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~ Glen ~