well, the only competition would be what, the Chinese and the Russians?
Amazing how for all those years BAe, Lockheed, Douglas, Sud-Aviation, Fokker etc. etc. could all make airliners but now consolidation is king. This has already bitten the US in the hindpart with the lack of home alternatives to the 767 for their tanker replacements.
Even in situations where "better" products exist on paper, airlines still buy others because of their needs (availability of typed pilots, existing fleet/maintenance facilities/spares).
Bottom line - the competition authorities in US/EU and the airlines wouldn't stand for it. So really this original question comes down to "who's best, A388/B748, A350/B787, 737NG/A320" and a consequent A v B flame war.