Virtually every airline offers a frequent flier loyalty program, but not all programs are created equal -- or are equally loved. In a new survey by Airfarewatchdog, low-cost carrier Southwest Airlines was ranked by frequent fliers as having the best loyalty program of all U.S. airlines. 

In the poll of more than 1,500 travelers, Southwest earned 32 percent of the votes for best frequent flier program, beating its runner-up by a wide margin: Delta came in second place with 17 percent of the vote. American Airlines was in third place with 14 percent of votes. 

Southwest was the only budget airline at the top of the list. Its Rapid Rewards program follows a system that more airlines are adopting: awarding points not on the basis of miles flown, but on the basis of dollars spent per ticket. The program is likely attractive to fliers because of its robust options for finding award seats. There are no seats limited to "award tickets" -- if a seat is open on a flight, Southwest customers can used their miles to book it. Coupled with Southwest's low fees -- Southwest doesn't charge for checked baggage, as so many airlines do -- Rapid Rewards offers good value for people flying domestically in the U.S.

Southwest also offers a Companion Pass -- the ability for anyone of your choice to fly free with you. Frequent fliers earn a companion pass once they fly 100 one-way qualifying flights or earn 110,000 qualifying points in a calendar year. 

Complete results of Airfarewatchdog's frequent flier survey: 

  1. Southwest -- 32 percent

  2. Delta -- 17 percent

  3. American -- 14 percent

  4. Alaska -- 11 percent

  5. United -- 11 percent

  6. JetBlue -- 8 percent

  7. Hawaiian -- 4 percent

  8. Frontier -- 2 percent

  9. Spirit -- 1 percent

  10. Allegiant -- 1 percent