Consumer debt levels are rising and reached more than $4 trillion earlier this year. It was a new record, and one that could continue climbing, as tougher economic times may be in store for Americans. Credit card debt in particular has also been rising, and that's why stocks like Visa (NYSE:V) and Mastercard (NYSE:MA) will continue to be hot buys for the foreseeable future.

However, for investors looking for the best growth stock, I think it's clear: the choice is Mastercard. Here are some of the reasons the company could offer superior growth.

Blockchain advantage

Both Visa and Mastercard are getting into blockchain, but over the long term, it's Mastercard that may prove to have the better strategy in what could be the next big growth opportunity for the industry. Visa already has a product in place based on blockchain architecture, B2B Connect. Aimed at making cross-border payments more seamless for businesses, it's a significant opportunity for the company. 

various credit cards laid out

Image source: Getty Images.

However, Mastercard is looking at making a big splash in cross-border transactions as well. Earlier this year, the company announced it was acquiring TransFast, which already has a significant network of its own, facilitating cross-border payments in more than 125 countries. 

That's going to go well with Mastercard's recent partnership with R3, which was announced in September. R3 is a blockchain software company that has companies from a variety of different industries using its Corda platform, which was designed to make business transactions safer. 

While both companies are making use of blockchain, Mastercard's ability to tap into R3's skills and expertise could give the credit card processor an important leg up in what's likely going to be a hotly contested market.

Mastercard has been growing faster

In 2018, Mastercard's revenues came in just under $15 billion for the full year, which was an increase of 20% from the prior year. By comparison, Visa's sales growth was a more modest 12% in its most recent fiscal year. 

And in its most recent quarterly results, Mastercard processed 21% more transactions than it did a year ago, compared to just 11.7% growth for Visa. Both companies did well on the top line, but there was a slight edge for Mastercard here as well, with its net sales rising 12.2% versus 11.5% for Visa. 

With Mastercard partnering with Apple (NASDAQ:AAPL) on its new Apple Card, there could be even more growth in store as the new card, which won't have any numbers on it, will give users some added security that could make it very popular.

Looking ahead

These two industry giants are often on an equal footing, but I'm convinced that the edge goes to Mastercard today. With a lot on the horizon and the company already generating some impressive numbers, it's hard not to like the stock as a long-term investment. Investors seem to agree, as Mastercard's stock has risen more than 40% year to date.