There’s nothing consumers like better than freebies, which may be part of the reason frequent flyer programs are so popular.

But as a consumer, you want to get the best value for your long-term investment in their service—especially when roughly seven percent of all airline flights are paid for with points or miles, according to accounting firm PricewaterhouseCoopers.

To help consumer decide on a rewards plan, WalletHub compared 10 of the largest domestic airlines’ frequent flyer programs across 23 key metrics, ranging from the value of a rewards points per mile to blackout-date policies. 

One of the trends uncovered in the study was that airlines, in general,  are lowering the value that consumers are reaping from their flying miles. "Only three of the 10 largest airlines are offering more rewards value in 2019 than in 2018, sweetening the pot by an average of 13 percent," WalletHub said.

The following rewards programs, in ascending order, have been ranked by WalletHub as giving consumers the best value:

10.  Spirit Airlines – Free Spirit

Spirit Airlines, headquartered in Miramar, Fla., is the seventh-largest airline in the U.S. Spirit offers flyers low-cost airfare and none of the frills. Its Free Spirit frequent flyer program, for example, does not partner with other airlines, and if you don’t use your rewards, they’ll expire. 

9.  Sun Country Airlines – Sun Country Rewards

Sun Country Airlines, headquartered in Eagan, Minn., is an ultra-low-cost airline. Since Sun Country offers value over amenities, it has eliminated point pools. Starting this year, frequent flyer points expire after 36 months.

8. Frontier Airlines – myFrontier

Frontier Airlines is an ultra-low-cost carrier headquartered in Denver. It is the eighth-largest commercial airline in the U.S. At $10.68 of rewards value per $100 spent, Frontier's program is one of only three that offers more value in 2019 than it did in 2018, when the return was $8.36 per $100 spent.

7. American Airlines – AAdvantage

Founded in 1926, American Airlines is headquartered in Fort Worth, Texas. It is the world’s largest airline, with flights to nearly 1,000 destinations worldwide. Despite its size, American is one of seven airlines offering less rewards value in 2019, at $8.13 per $100 spent, than it did in 2018, when the value was $8.23 per $100 spent.

6. Alaska Airlines – Mileage Plan

Alaska Airlines, headquartered in Sea Tac, Wash., is the fifth-largest airline in the U.S. WalletHub says that, at $18.12 per $100 spent, Alaska offers the second-highest rewards value of the 10 carriers surveyed. However, that is less value than it offered frequent flyers last year, when the value was $19.87 per $100 spent. 

5. Hawaiian Airlines – HawaiianMiles

Hawaiian Airlines, based in Honolulu, flies to 28 destinations and is the 10th-largest commercial airline in the U.S.. WalletHub says that Hawaiian Airlines offers the most rewards value, at $21.29 per $100 spent, and is one of only three carriers offering frequent flyers more value for their loyalty in 2019, than it did in 2018.

4. Southwest Airlines – Southwest Rapid Rewards

Southwest Airlines, headquartered in Dallas, is the world’s largest low-cost carrier. There are no blackout dates in its rewards program, even on holidays; no fees to change or cancel a rewards flight; and no seat restrictions on rewards flights. However, points will expire if there is no qualified earning activity for 24 months.

3.  JetBlue Airways – TrueBlue

JetBlue Airways, the seventh-largest U.S. airline, is a low-cost carrier headquartered in New York. WalletHub says that at $11.49 per $100 spent, JetBlue is one of only three airlines surveyed offering frequent flyers more value for their rewards membership in 2019 than it did in 2018, at $11.15. It is also one of only two airlines that do not have an expiration date for reward points.

2.  United Airlines – MileagePlus

Founded in 1931, United Airlines is headquartered in Chicago. Because it partners with 39 other airlines, the second-highest number among carriers surveyed, loyalists have numerous travel options worldwide. However, at $9.52 per $100 spent, United is offering frequent flyers less value for their loyalty in 2019 than it did at $10.05 per $100 spent in 2018.

1.  Delta Airlines - SkyMiles

Founded in 1924, Delta Air Lines is headquartered in Atlanta. For a fourth straight year, WalletHub has named Delta’s SkyMiles program the best deal for consumers. It is one of only two carriers without rewards point expiration dates. It also partners with 40 carriers, the most of all airlines surveyed. However, like many other carriers surveyed, Delta is offering frequent flyers less value for their loyalty in 2019, at $12.05 per $100 spent, than it did in 2018, at $12.90 per $100 spent.

The full report can be viewed here.