NEW YORK (TheStreet) -- The credit card business is booming. There are more cards with more debt on them. Better still, consumer confidence is up as the big holiday spending days approach. So it might be a better time to invest in plastic rather than swipe or tap it.

However, words of caution are in order. While there are only four choices, Visa (V) - Get Report , MasterCard (MA) - Get Report , Discover Financial Services (DFS) - Get Report  and American Express (AXP) - Get Report  are nowhere near sharing equally in the good times.

Also, there can be too much of a good thing, as there was in the days leading up to the Great Recession. Credit card debt shot up to averaging $8,800 per household only to plunge on defaults to $6,700 before climbing back up to reach the current $7,300.

Visa is the undisputed leader with nearly half the market. MasterCard is next with 30%. Together, they not only dominate the industry, they are in a different and, more important, better business than Discover and American Express.

The latter two actually issue credit cards while Visa and MasterCard are technology companies. Their job is simply to process financial transactions, taking out 2% to 3 % from every one, and they benefit enormously from an economy of scale. Indeed, they are among the most profitable companies on earth, with profit margins, which have been spreading with growth, of 43% and 38%, respectively, versus 8% for all companies.

In no small measure due to its size, Visa gets the nod over MasterCard in a number of other financial categories including sales, earnings and growth prospects.

Not surprisingly, the market likes Visa a little better, too. Its shares, at close to $76, have gained 49% over the 52 weeks while MasterCard, at $97, has been up 37% for the same period versus just 8.8% for the S&P 500. Visa has been ahead of MasterCard in the market ever since the 2011 correction -- though both have racked up impressive triple digit gains since that time.

Going forward, Visa's stock looks to have the edge again. While Visa is the stronger company, both stocks start from near identical positions. They are near 52-week highs and trade at the same price to earnings multiple, 29.

That these stocks are trading at a premium of 50% to a multiple of 18 for the S&P 500 may give investors a reason to look more closely at the other two players. Both shares of Discover and American Express are selling at outright bargain prices after losing ground over the past year. Their multiples are a modest 11 and 13, respectively.

Though down, they are hardly out. The credit card business is not a zero sum game. The 40% of all financial transactions in the U.S. that are done with cash rises to 85% globally, leaving a lot of room for growth for each one of these four international businesses.

Discover, however, appears to be the better bargain of the two. Not only is it cheaper, it has a bigger share of the market and is a more profitable company, with margins of 27% to American Express's 16%. Furthermore, shares of American Express were hurt this week when Zacks Investment Research issued a sell rating on its shares.

This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.