Tired fliers often think about how nice it would be to stretch out across a whole row of economy-class seats and take a nap. But let’s face it: airline seats were simply not designed for napping. That is, until Air New Zealand introduced its "Sky Couch," with flip-up seats created for just that purpose.

Comforts like these are just one reason ANZ was voted the No. 4 World’s Best Airline in our annual World’s Best Awards, where our readers ranked 76 airlines based on cabin comfort, in-flight service, customer service, value, and food.

So which airlines came out on top? International airlines virtually own the top 20 World’s Best Airlines; only two U.S. carriers made the list. Asian and Middle Eastern carriers dominate the top 10, with scores that are remarkably consistent from year to year, such as this year’s No. 3-ranked Etihad Airways, a United Arab Emirates-based carrier.

One thing is clear: the quest by the top-ranked airlines to become even better is raising the stakes. The leading carriers are vying to upgrade seating in every class—so-called thin seats in economy that allow everyone to recline without disturbing neighbors are all the rage among Asian carriers. For example, Korean Air, which ranks No. 9, earned points for its ergo-friendly “slim seats.”

But ultimately, it’s service that makes—or breaks—an airline’s ranking. Great on-the-ground customer service is vital to a high ranking. But even more important—and more highly weighted—is in-flight service. After all, you probably won’t remember a cramped coach seat, but you’ll definitely remember (and possibly complain about) a rude flight attendant.

So check out the World’s Best Airlines:

No. 1 Singapore Airlines

In every category of our awards, Singapore Airlines consistently outpaces the pack. Even though its scores went down—slightly—since 2010, it still beats the competition, thanks to innovations such as in-flight Wi-Fi, entertainment systems that allow you to play your own video and audio through your iPod, and USB ports for all passengers. But it’s the famous in-flight service—credit the legendary Singapore Girl in her sarong designed by Parisian couturier Pierre Balmain—that still keeps the rest of the pack at bay.

No. 2 Emirates

Ranked No. 2 as it was in 2010, the airline has improved its scores and even taken on a better reputation for value and food, while steadfastly maintaining its reliability for both in-flight service and customer service. Its reputation as an innovator—it pioneered laptop Wi-Fi in 2004 and mobile phones back in 2008—is another reason it remains one of our readers’ favorites.

No. 3 Etihad Airways

High marks all around, but the second-highest scores for in-flight service are the hallmarks of this flag carrier of the United Arab Emirates. On-board comforts include Cradle Recline seats in economy class, for a seat pitch of 32 to 34 inches. Apart from 600 hours of in-flight entertainment, you can charge and play your iPod and other devices through its E-BOX System.

No. 4 Air New Zealand

Improved cabin comfort and an increase in value helped Air New Zealand climb up the ranks from seventh position in last year’s poll. Food, in-flight service, and customer service also went up, just enough to nudge the carrier into our top five category. The airline’s Skycouch—three economy seats that convert to a bed—must have helped the cabin comfort ranking.

No. 5 Virgin America

The highest-ranking domestic airline in our poll—and the only one in the top five—Virgin America scores impressively high marks with incremental improvements in every category. In other words, the airline founded on Virgin Atlantic’s formula for service, innovation, and attitude just keeps on getting better. The combination of low fares and tech improvements—it’s installing Lufthansa Systems’ BoardConnect to radically upgrade its Red entertainment system to enable you to use your own devices—keep it at the forefront.

No. 6 Virgin Atlantic Airways

Close on the heels of its American offspring comes Sir Richard Branson’s flagship carrier, which pioneered cheek and style (not to mention seat-back video and amenity kits in every class) and gave the customers what they wanted (including pioneering economy plus). Fliers seem to like it, judging by the scores that have edged up in every category since last year. But since the other airlines did even better, it slipped from last year’s No. 4 position.

No. 7 Cathay Pacific Airways

Cathay has always played second fiddle to Singapore when it comes to Asia-based airlines, and despite incremental improvements in every category except food—down just a tad—it slipped down from last year’s No. 5 ranking. But a flight on Cathay remains a singular pleasure. The “fixed shell” economy seat means that no one can recline into your space (your seat reclines within your space).

No. 8 All Nippon Airways

The carrier that used to exist in the shadow of Japan Air Lines continues to move up the ranks from last year’s 11th position—and way ahead of JAL. Marked improvements in cabin comfort, in-flight service, customer service, and value helped. And that’s even before it introduced such innovations as women’s-only bathrooms with Japanese-style bidet-toilets on the new Dreamliner 787.

No. 9 Korean Air

Korean Air edged up from tenth place last year, with readers giving it slightly better scores in every category. Noteworthy are the ergonomically designed “slim seats” in economy with 34-inch pitch, not to mention the USB ports and chargers at every seat. The menus—Chinese, Korean, Japanese, and Western are standard on every flight—have also improved.

No. 10 Thai International Airways

While Thai Airways improved in every category, other airlines did more. Hence the fall from last year’s No. 8 position. But it did rank higher with customer and in-flight service, as well as food. After all, this carrier takes care of kids, with free toys, games, and books, and offers private Premium Economy cabins with 42-inch pitch seats with 122 degrees of recline. It’s just that the other guys pushed the envelope a bit further.