It's incredibly difficult to rank airlines as a whole. Each has strengths and weaknesses. Just on the most basic level, look at BA vs LH - I'd far rather be on BA in Y or J, but no question I would be on LH if I was in F.

AA's new 77W J seat is superb also - but they only have 6 or 7 frames with that seat. So do you judge AA by the new seat or the terrible old seat?

Domestically in the US, Delta seems to have the best experience for non-status pax. AA arguably is the best for FFs and the FFP is the best, while UA has the most robust network and best overall J hard product. US has its Advantage Fares program which is extremely useful for buying close-in tickets.

Generally, imo Asian and Middle Eastern airlines have the highest overall quality, followed by EU Airlines, then US airlines. Lots of variance in the quality of South American and African airlines.