"It struck me how wide the depth was of frequent-flier satisfaction," says Brian Karimzad, director of MileCards.com. "When you look under the hood, while each program can get you anywhere in the world for close to the same mile price, there are differences that separate how consumers view them."
Here are the seven best and worst parts of the nation's five largest airline miles programs, based on a MileCards.com survey in December 2013 of 1,600 members of frequent flier programs.
Easiest to redeem your miles: Southwest Airlines.
About 64% of Southwest's frequent flier members said it was easy to get an award. American Airlines came in second at 56%.
Hardest to redeem your miles: US Airways.
About 17% of US Airways frequent flier members said it was impossible to get an award. Delta Airlines came in second at 16%.
Least friendly rewards website: Delta.
About 26% of Delta frequent flier members said the rewards website was hard to use and it was difficult to find the award they wanted. US Airways came in second at 25%.
Most loyal customers: United Airlines.
About 41% of United's frequent flier members almost always buy United flights versus other airline flights because they want to earn miles. Southwest and Delta tied for last at 33%.
Points are considered worthless: US Airways.
About 11% of US Airways frequent flier members said their miles are worth nothing. Southwest came in second at 6%, while Delta, American and United all tied at 5%.
Lowest satisfaction overall: US Airways.
Only 43% of US Airways frequent flier members would recommend the program to a friend. Delta was the only other airline to come in under half at 49%.
Highest satisfaction overall: Southwest.
About 62% of Southwest frequent flier members would recommend the program to a friend. United came in second at 55%.