Airline Alliance: Which Airline Alliance Is Best?
So what’s the big fuss about airline alliances, and why should you familiarize yourself with them? Simply, they make international travel easier and more cost/time effective for you, the customer.
Airline alliances often fly under the radar when it comes to the general public, but they are an increasingly important part of the airline industry. These industry arrangements often involve multiple airlines, various codesharing agreements, and a general sense of co-operation. Some members of airline alliances even use unified liveries.
Three major alliances.
The goal of these coalitions is to provide travelers with access to more destinations, streamlined connections, and competitive pricing due to smaller operational costs. Of course, this has some benefits on the airlines' bottom line, by cutting down on overlapping operations in shared markets and by funneling travelers through partners instead of a competitor's plane.
Oneworld

Oneworld’s premium status memberships are structured into three levels. The top being Emerald, followed by Sapphire, and the lowest tier membership is Ruby. Similar to the other alliances, Oneworld elites receive lounge access and added benefits like free checked bags and occasional upgrades. Flyers that have elite status with any alliance member frequent flyer program will be granted the corresponding tier in the Oneworld program. Oneworld elite tiers are recognized on all flights ticketed by member airlines.
For U.S. based frequent flyers, American Airlines is the gateway airline into Oneworld membership. However, those who accumulate miles with the airline will find it hard to redeem miles using the AAdvantage program on other member airlines. American only offers a snippet of available awards inventory on their site, and the amount of partner flights displayed is downright abysmal, with many airlines not displayed at all. Member British Airways is not much better. While it offers a better selection of flight options, they come with astronomical fuel surcharges that generally wipe out any savings you thought you'd get by redeeming for a "free flight."

American Airlines
British Airways
Cathay Pacific, Hong Kong
Finnair, Finland
Iberia, Spain
Japan Airlines
LAN Airlines, Chile
Malaysia Airlines
Qantas, Australia
Qatar Airways
Royal Jordanian
S7 Airlines, Russia
SriLankan Airlines
TAM Airlines, Brazil
Star Alliance

StarAlliance breaks down its elite status into two levels: Silver and Gold. Gold status in StarAlliance’s program is generally harder to reach for the average traveler, as it requires reaching the premium-to-highest levels of a member airline's frequent flyer program. Members who attain Silver and Gold membership within StarAlliance’s elite program receive benefits like extra baggage allowances, preferred boarding, and seat assignments. With the most extensive network of members, StarAlliance also boasts the most airport lounges amongst the three major alliances. Airport lounge access varies per airline and is dependent on which level of status you have within the program, so it's best to check in advance if you qualify for entry.
Many flyers based in North America will be familiarized with the StarAlliance via United Airlines or Air Canada. Using United Airlines MileagePlus program and search feature on their website, it's effortless to view member airlines' award availability. Awards at the Saver Level will cost the same amount of mileage no matter which partner airline your flights are operated on. Business and First Class awards will require extra mileage than flying on award flights solely operated by United. Air Canada is planning to overhaul its frequent flyer set-up by ditching current Aeroplan for a loyalty program of its own starting in June 2020.

Aegean Airlines, Greece
Air Canada
Air China
Air India
Air New Zealand
All Nippon Airways, Japan
Asiana Airlines, South Korea
Austrian Airlines
Avianca, Colombia
Brussels Airlines, Belgium
Copa Airlines, Panama
Croatia Airlines
EgyptAir
Ethiopian Airlines
EVA Air, Taiwan
LOT Polish Airlines
Lufthansa, Germany
Scandinavian Airlines
Shenzhen Airlines, China
Singapore Airlines
South African Airways
Swiss International Airlines
TAP Portugal
Thai Airways
Turkish Airlines
United Airlines
SkyTeam

SkyTeam splits its premium levels into two levels: Elite and Elite Plus. Status is awarded to frequent-flyers who have reached premium levels in a member airline. For example, a Delta Silver Medallion member will receive SkyTeam Elite, while Delta Gold or above flyers will receive Elite Plus. As with the other alliances, benefits for SkyTeam Elites are priority boarding, check-in, and preferred seating. SkyTeam Elite Plus members have additional perks, including extra baggage allowances and airport lounge access.
Delta Air Lines is the carrier that the majority of U.S. customers will be introduced into the SkyTeam network. Delta’s SkyMiles loyalty program doesn’t publish an award chart for flight redemptions, creating a guessing game on how many miles are required for a particular award. With frequent devaluations and the removal of tables, the moniker SkyPesos is bandied about regarding the program in the frequent flyer community. Air France, KLM, TAROM, Kenya Airways, and subsidiary airlines, have created a unified frequent flyer program titled Flying Blue. SkyTeam elite status is generally easier to achieve using Flying Blue over SkyMiles unless you're a Delta regular and dish out enough money with the airline to qualify.

Aeroflot, Russia
Aerolineas Argentinas
Aeromexico
Air Europa, Spain
Air France
Alitalia, Italy
China Airlines, Taiwan
China Eastern Airlines
Czech Airlines
Delta Airlines
Garuda Indonesia
Kenya Airways
KLM
Korean Air, South Korea
Middle East Airlines, Lebanon
Saudia
TAROM, Romania
Vietnam Airlines
Xiamen Airlines, China