The list is almost a case of just naming every major airline in the world

"The Top 25 premium airlines are Air New Zealand, Qatar Airways, Etihad Airways, Korean Air, Singapore Airlines, Qantas, Virgin Australia/Virgin Atlantic, EVA Air, Cathay Pacific Airways, Emirates, Lufthansa / Swiss, SAS, TAP Portugal, All Nippon Airways, Delta Air Lines, Air Canada, British Airways, Jet Blue, JAL, Vietnam Airlines, Turkish Airlines, Hawaiian, KLM, Alaska Airlines and United Airlines."

I also have zero idea how anybody can group Virgin Australia and Virgin Atlantic together as one when there is no relationship between the two (other than Branson having a very small stake in Virgin Australia) and both offer very different product offerings.