American Express Membership Rewards points are among the most valuable and versatile points you can collect, largely because they are transferable to so many partner airline programs. There are several low value uses of Membership Rewards points such as using points to offset charges, shopping on Amazon, and redeeming for gift cards; but all of these uses will net you less than 1 cent per point which is a terrible value. As with any transferable points currency, you will get the best value by transferring your points to one of their partner airline or hotel programs and redeeming them for sweet spots within those programs. However, it is almost always a good idea to store your points with American Express until you are willing to actually book a reservation with one of their partners. This is because each individual program is subject to unannounced devaluations, and by keeping your points with American Express, it shields your points from unexpectedly losing value.
Chase Ultimate Rewards points are one of the top 3 most valuable points currencies you can collect largely because you are able to transfer them to other mileage programs and use the sweet spots in their programs. Technically, there are three possible uses of Ultimate Rewards points: redeeming for cash back, booking air travel with your points at a value of either 1.25 cents/point or 1.5 cents/point depending on the card, or transferring them directly to an airline or hotel partner. The third option will almost always get you the highest value per point as long as you book your awards wisely.
Citi ThankYou points are the least widely known of the three major transferable points currencies. Chase Ultimate Rewards points and American Express Membership Rewards points are most likely the first two currencies that spring to mind when you think of transferable points; and with good reason as most people would agree that they are in general more valuable than Citi ThankYou points. However, while ThankYou points might not be the most valuable currency, there is still plenty of value to find with their partners. As is the case with every transferable points currency, you will get the best value from your Citi ThankYou points by transfering those points to one of their partners rather than redeeming them for cash back or using them to book through the Citi Travel Center.