If you live near a hub for a particular airline you may be tempted to exclusively earn their own miles without a second thought. Examples abound: if you live near Philadelphia, earn American miles; if you live near San Francisco, earn United miles, etc. Unfortunately, if you act solely on that impulse, you will be missing out on a whole host of options that could be of better benefit to your future travels.
Enter: transferable currencies. Instead of only earning miles with one airline you can earn points that can be turned into miles for various airlines at the drop of a hat.
You see, banks like Chase, American Express, Citibank, and more want to entice you to use their credit cards by offering the incentive of earning points within their own ecosystems. These points are very lucrative and more often than not a better deal for your use booking award tickets. As you can see below there are a wide variety of transfer partners you get access to with these currencies.
But why do I consider transferable points to be better than airline miles? For two main reasons:
1) I like having options of where I can transfer my points. Say I want to fly from New York to Zurich. If I only had United miles it would cost 88k/person one-way in business class. Having transferable points gives me the option to move them to Air Canada, costing me only 60k/person one-way! That saving of 28k could go towards my next trip!
2) Transferable currencies often have bonuses. In an effort to entice you to earn and use their points, banks often offer extra points when you transfer from their ecosystem to airlines or hotels. Right now there are transfer bonuses from Amex and Chase that would save a lot of points for future redemptions.
There are sometimes reasons to focus on one particular airline mileage program. Perhaps you travel consistently between two or three airports that all use the same airline. Or, maybe you find it beneficial to earn status through flying one airline. Those can be good reaosons if you calculate out the benefit properly.
In my experience, however, having options is better than not so I usually recommend earning transferable currencies.
