What are the best and worse frequent flyer programs in 2018?

With U.S. airlines expected to carry more than 600 million passengers on domestic flights this year and credit card debt levels exploding, airfare savings are becoming more important to consumers this year.

To help travelers make the best decisions on frequent flyer programs, WalletHub, a personal-finance website, released its report Wednesday on “2018’s Best Frequent Flyer Programs,” which ranks the 10 largest domestic airlines based on 23 key items. They range from the value of a point/mile to blackout dates for rewards flights. WalletHub’s report also features a custom calculator that allows users to personalize the results based on their own budgets.

Highlights from the report include:

• Delta SkyMiles is the best frequent flyer program for the third straight year.
• The average airline rewards program gives frequent flyers 12 percent off their airline spending. And they’re all free to join. 
  Hawaiian Airlines offers the most rewards value to frequent flyers, $19.95 per $100 spent, with Alaska Airlines coming in second, $19.87 per $100 spent.
  
• Four of the 10 largest airlines are offering more rewards in 2018 than in 2017, an average of 20 percent.
• Delta Air Lines and JetBlue Airways are the only two major airlines whose miles don’t expire because of inactivity.
• The Frontier Airlines Credit Card and the Lufthansa Credit Card are 2018’s best airline credit cards, according to WalletHub’s editors