The Oneworld Alliance is my favorite of the airline alliances.
Reasons? Great airlines, good programs, excellent benefits.
Before we go deeper into Oneworld, here are some basics about alliances.
The goal of an alliance is to make it easier for travelers to standardize benefits in a group of airlines. Once you fly enough with a single airline in the alliance and earn status, that status would be matched to an alliance status so that you can enjoy similar benefits across all airlines in the alliance. For example, if you fly Cathay Pacific (oneworld Alliance member) frequently and you get, let's say, SILVER status, which is matched to RUBY level in the oneworld system, you can enjoy the Oneworld RUBY benefits when flying American Airlines (also a participating airline in Oneworld) such as priority checkin, priority boarding etc.
There are primarily 3 alliances: Oneworld, Star Alliance, and Skyteam.
In Oneworld, there are 3 status tiers. Ruby, Sapphire, and Emerald. Airlines might call each of their own status a different name, but each will correspond to a Oneworld tier (Ruby, Sapphire, Emerald).
For instance, take a look at Cathay Pacific's Marco Polo Club. They have 4 levels in their program: Green, Silver, Gold, and Diamond. Green is the entry level without substantial benefits; Silver corresponds to Oneworld Ruby; Gold corresponds to Sapphire; and Diamond corresponds to Emerald.
Each tier grants different benefits. Although it varies with airlines, Oneworld Ruby, for instance, often gets business class priority boarding and priority check-in. Sapphire can have business class lounge access in addition to the perks that Ruby offers. Emerald members would have first class lounge access, first class boarding, and first class check-in.
The difficulty in attaining each of the tier varies by airlines. Generally speaking, the hardest to achieve status on is Cathay Pacific Marco Polo Club, which requires 300 club points for Silver (Ruby), 600 points for Gold (Sapphire), and 1200 for Diamond (Emerald). To put it in perspective, to upgrade to Diamond would require 20 roundtrips on HKG-LAX on Discounted Economy Class in a year. Yikes. The easiest, meanwhile, is often considered to be with American Airlines. One would need 25,000 Elite Qualifying Miles to attain the status in addition to spend requirements to achieve their Gold Status (Ruby) - which already grants benefits like upgrades. I will be discussing the specifics of each program in further posts, but if you are a beginner and live in the US - try starting with American Airlines AAdvantage!
Regarding the products on Oneworld participating airlines, some of them are top-notch. Qatar Airways, for example, has Qsuites in business class - arguably the best business class in the world; Cathay Pacific, in my opinion, has the most consistent First/Business Class; JAL has the best economy product in my opinion. Below are just some of my favorites about the Oneworld.
Favorite Airlines in the alliance: Cathay Pacific, JAL, Qatar. Superb Products.
Favorite Programs in the alliance: British Airways Executive Club, American Airlines AAdvantage, Cathay Pacific Marco Polo Club
Favorite Perk: First Class Lounge Access as Emerald. (which is not offered through Star Alliance/Skyteam)
Favorite Oneworld First Class Lounge (can be accessed through Oneworld Emerald Card): Cathay Pacific First Class Lounge Hong Kong - The Pier First
Favorite Oneworld Business Class Lounge (can be accessed through Oneworld Sapphire Card): Cathay Pacific Business Class Lounge Hong Kong - The Pier Business