Reuters reports that Panama’s Copa Airlines and U.S. low-cost carriers Spirit and Allegiant are the three most profitable carriers in the world by operating margin, respectively, according to a ranking of 75 companies published Monday by Airline Weekly.

Budget carriers claimed six of the top 15 spots, which suggests that their no-frills strategy is paying off as travelers hunt for the lowest fares. U.S. legacy carriers all ranked in the top half, while a number of airlines in Asia had negative income and the poorest results.

Copa kept about $0.22 of every dollar of revenue for the year ending June 2014, according to the ranking. Spirit kept about $0.18 while Allegiant kept about $0.16 – both more than triple United Airline’s margin of about $0.05, which stuck the carrier in 34th place.

Delta ranked 11th, Southwest came in at 14thand American – the world’s largest airline by passenger traffic – ranked 15th.

To be sure, the legacy carriers trumped their low-cost rivals in actual income earned. Delta’s operating income last quarter was about $1.6 billion whereas Spirit’s was almost 15 times less, at about $105 million.

The results underscore how U.S. airlines have shrunk their capacity to match consumer demand, following years of empty seats and bankruptcies, according to Airline Weekly’s Managing Partner Seth Kaplan.

This in part explains why JetBlue, which has come under criticism for not charging passengers for their first checked bag – a money-making tactic widely adopted by its peers – still ranked 19th with an operating margin of $0.08.

“Everyone would prefer flying JetBlue to Spirit” because of its free snacks and wifi, Kaplan said. However, they instead choose Spirit’s lower fares.

Spirit also beefed up its margin by outfitting its Airbus A320 planes with 178 seats while JetBlue’s only have 150 – which helps the budget carrier distribute its costs across more passengers, Kaplan said. He added that JetBlue would have ranked even lower had the metrics considered airlines’ debt.

So which carriers came in dead last?

Embattled Malaysia Airlines, which lost two of its planes and their passengers in tragedies this year, ranked 71st with a negative operating margin of $0.08.

Slightly worse were Tigerair and Jet Airways, followed by two sharp drops: SpiceJet at negative $0.16, and Pakistan International at negative $0.27 (for the year ending December 2013).

While the market for travel in Southeast Asia is growing, it has become over-saturated with airlines trying to take a piece of the action, Kaplan said.

The ranking was based on operating income and did not account for interest, taxes and other factors because countries have different accounting standards, Kaplan said. Airlines that do not release audited financial statements, such as Etihad Airlines and Qatar Airways, were not included in the list. (Reporting By Jeffrey Dastin; Editing by Alwyn Scott and Andrew Hay)