Here are the best frequent flyer programs in the U.S.

The U.S. is “a nation of points hoarders,” a survey on frequent flyer programs by J.D. Power and Associates found.

Almost three-quarters of respondents to the survey said they save their frequent flyer miles to spend them on big rewards instead of burning them on smaller perks.

The ease of earning or redeeming those miles for a dream vacation or an upgrade to a luxurious first-class suite is the top factor in J.D. Power’s assessment of U.S. airlines’ frequent flyer programs. The company conducted the survey of 3,025 people in May and June, but also took into account program benefits, account management and how well the airlines communicated with loyalty program members.

J.D. Power ranked the airlines on a 1,000-point scale. While the industry average is slightly higher than last year, the programs are still extremely complex and only about half of members completely understand how they work, J.D. Power said.

JetBlue Airways’ TrueBlue program topped the list for a second year in a row and its score rose slightly from a year earlier. Southwest Airlines’ Rapid Rewards program knocked Alaska Airlines from the second spot.

Here’s how airlines’ programs stacked up: