American ExpressAmerican Express ( AXP) may not be the biggest payment network on earth, but it's certainly one of the most attractive from an investment standpoint. The $83 billion financial firm has spent the last 163 years building up one of the most storied brands in the world -- and its flagship charge card products remain extremely attractive six decades after the first green card was issued. >>4 Big Stocks on Traders' Radars AmEx is the bane of many of its merchants. The firm is known for charging the highest fees of any card network, but merchants continue to pay those fees because of the dollar volume that the firm's network generates. American Express isn't the largest payment network, but its per-capita spending dwarfs the numbers generates on Visa ( V) or MasterCard ( MA). The firm's spend-centric model means that it's less incentivized by the high card balances that got other lenders in trouble in 2008, and newer partnerships with third-party issuers mean that it should stay that way. The huge swath of consumer data that American Express retains on its cardholders is another important asset that it's only just starting to monetize in a meaningful way. As marketers focus increasing resources on targeted ads, AmEx's database gains more and more value. In the meantime, a skew towards more affluent consumers in its membership rolls should mean a bigger impact from consumer spending increases this year.