As was the case last year, not a single airline from Europe or the Americas made the overall top 10 list. That is something of a surprise considering Delta, like Qatar Airways, introduced a new all-suites business class last year. Also like previous years, the rankings are significantly skewed toward the Asia-Pacific region. This should not be a surprise considering the massive growth of aviation in that part of the world, which is only projected to continue increasing in the coming decades.
While the above search engines are great, they do not always include small airlines, especially in less popularly booked routes and/or in remote regions. If you're flying somewhere obscure, Google search and ask around if there exists a local airline. While in South America we learnt that the LADE Air in Argentina (run by the military) has cheap flights to Patagonia, which is of course not listed in mass search engines online.
If you're flying somewhere that involves a transfer, say from Canada to Australia which typically involves Canada to LA, then LA to Australia, consider that it may be cheaper to book these two legs separately on your own by adding another destination to your trip. It should go without saying that in doing this, you should not book tight layovers. I repeat: do not book layovers that are hours apart! This approach is for those who want to create an additional destination of a few days or more, before catching their next flight. The one exception is when booking with Kiwi.com, who offer their own guarantee on making connecting flights even when not with the same partner airlines.
Another thing to note when you're booking your flight tickets online is to consider extra fees and "hidden" charges such as credit/debit card fees, baggage, meals, certain seats, extra leg room et cetera. Factor all these in before you compare between different airlines and flights before making the final purchase. Most online travel portals require you to pay via credit card, and may charge you a hefty credit card fee. But some sites also accept PayPal (including American Airlines website aa.com, Agoda.com, hotels.com). If you buy tickets directly from most airlines, you also won't be charge a credit card fee, and you should take those charges into consideration when choosing between booking through an airline website or other travel websites. Some online travel agencies let you pay via wire transfer from your bank account.
Many of these budget airlines have their own airline rewards credit cards, and most of them offer a major signup points bonus. For example, the Southwest Rapid Rewards Plus card from Chase offers 40,000 points after spending just $1,000 in your first three months. However, a general travel rewards credit card such as the Chase Sapphire Preferred is the best option for most people, as you have the flexibility to redeem your points towards a wide variety of airlines and hotels. You'll receive 60,000 bonus points worth $750 through the Chase Ultimate Rewards program after you spend $4,000 in the first 3 months of your account opening, and the card features no foreign transaction fees. Compare this card to other travel cards here.