I travel constantly
My votes go to:
Emirates
Qatar
Turkish
Singapore
I often fly British from EZE to prague via lhr and it's not so bad. Far better than Alitalia or Iberia. Don't even mention aerolineas or air Europa
Us airlines quite bluntly suck!
In South America best is still probably the new Latam
I'm currently in Japan and find Japanese carriers quite good as are many other Asian one, I.e. Cathay pacific, ANA,JAL, THAI
Was not too long ago on Air Koryo from Beijing to Pyongyang like the old Soviet Aeroflot days!
And must confess even though the planes are old although now due to be renewed, airlines in Iran were not bad!
Happy flying