There are a lot of credit cards options for consumers in the U.S. -- NerdWallet allows you to compare 1,714 of them! And for millions, practically not a day goes by without another offer from another company for another credit card shows up in the mail. According to Experian, there are slightly over 2 open credit accounts per individual with credit history.

But one company has claimed the title as having the most customers who enjoy it the most.

Was it American Express (NYSE:AXP)? Despite its title last year, it turns out one competitor beat it, as it came in second.

How about Capital One? Or maybe another big bank? Absolutely not.

I won't keep you waiting, it was Discover (NYSE:DFS). And it had a remarkable 2013 to surpass American Express. But remarkable has characterized just about everything both of these companies have done over the years.

The powerful lead

Every year, Satmetrix, a consultancy focused on customer experience, releases its Net Promoter Score (NPS),which reports customers' opinions of 219 brands in 22 industries through a survey of more than 23,000 people.

The Net Promoter Score is determined by the question which asks simply, "How likely is it that you would recommend [Company X or Brand X] to a friend or colleague?"

It then takes those customers deemed "promoters" -- those who respond with a 9 or 10 on the 10 point scale to the question above -- and subtracts out "detractors," who rank it six or less.

And as you can see below, the lead Discover and American Express have over the banks which issue credit cards is truly remarkable:

Source: Satmetrix US Consumer Credit Cards Net Promoter Study 2014

And it wasn't just that the total scores of Discover and American Express were impressive, but as Brendan Rocks, a Data Scientist at Satmetrix, noted, "one of the two is in the top spot for everything except for card is widely accepted."

Things like, customer service, online experience, overall value for money, rewards and offers, buyer protection, and much more. The reason for the sizable lead for these two is justified.

As Satmetrix notes, the bank in last place, Citigroup (NYSE:C) delivered improvement over where it stood in 2013, with its total score rising by 12 points. But to truly put it in perspective, consider that 27% of its customers are still deemed as "detractors." By comparison, just 12% of those at Discover rank it a six or below, and that number stands at 15% for American Express.

Although Citigroup may be improving, it's important to note this isn't just a one time lead for Discover and American Express. Over the last decade, each have had customers who continuously enjoyed the products and services the credit card companies offer more than industry:

Source: Satmetrix US Consumer Credit Cards Net Promoter Study 2014

As you can see, American Express and Discover delivered the services to customers that not only satisfy them -- they also rank first and second, respectively, in the most recent J.D. Power Credit Card Satisfaction Study -- but also make them more likely to recommend those brands to others.

The importance of customers

As previously noted, in 2005, Warren Buffett said:

If we are delighting customers, eliminating unnecessary costs and improving our products and services, we gain strength. But if we treat customers with indifference or tolerate bloat, our businesses will wither. On a daily basis, the effects of our actions are imperceptible; cumulatively, though, their consequences are enormous.

Delighting customers doesn't simply make those with the cards happy, but the investors as well.

Source: Company Investor Relations.

After all, as you can see to the right, consider that despite the fact Citigroup added half a million more credit card accounts in North America over the last year, the average loans it issued fell by $2 billion or 3%.

By comparison, Discover has seen its average loans rise by $2.7 billion, or 6%.

This loan growth will have an impact to the bottom line of both banks.

And speaking of Warren Buffett and how strongly he emphasizes customer satisfaction, he doesn't just say it with his words, but his wallet too. His company, Berkshire Hathaway (NYSE: BRK-A)(NYSE: BRK-B), owns nearly 15% of AmEx, in a position worth more than $14 billion.

Patrick Morris owns shares of Berkshire Hathaway and Discover Financial Services. The Motley Fool recommends American Express and Berkshire Hathaway. The Motley Fool owns shares of Berkshire Hathaway, Citigroup, and Discover Financial Services. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.