From Sept. 1, 2011, to June 5, 2015, I managed Tier 1 Investments, a Motley Fool real-money portfolio that outperformed the market by more than 40% from inception to close. Within Tier 1, I sought out companies with the strongest competitive advantages, largest growth opportunities, and best management. I call these businesses Tier 1 enterprises, and no company fits that description better today than (NASDAQ:AMZN). In fact, if I could buy only one stock, Amazon would be it.

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A deep and widening moat

Amazon is dominating the war for online commerce: 55% of consumers begin their search on the retail juggernaut's website when shopping online -- up from 44% in 2015 -- according to a recent report [opens in PDF] by BloomReach. Even more impressive, 90% of consumers will check Amazon even if they've found their product elsewhere. 

Helping drive these results are Amazon's powerful competitive advantages. First, the fact that Amazon doesn't have to maintain physical store locations gives it a lower cost structure than its traditional-retail competitors, which Amazon then passes on to customers in the form of lower prices. Second, Amazon is able to offer a wider selection of items than could be housed by bricks-and-mortar storefronts. Third, Amazon is a trusted brand with tremendous mindshare among consumers, as the BloomReach survey results show. Together, these advantages create a wide moat around Amazon's core online retail operations that its competitors simply can't surmount.

Massive growth opportunities

Even after two decades of torrid growth, the rise of e-commerce is still in its early innings. Online sales comprise less than 10% of retail sales, with research company eMarketer estimating that retail e-commerce sales will increase to more than $4 trillion in 2020, up from about $1.5 trillion in 2015. With millions more people gaining access to the internet every year, and an expanding global middle class ushering in a time of increased prosperity for millions of emerging-market consumers, e-commerce appears set to grow at a rapid pace for at least another decade, and likely much longer. Amazon stands to benefit from this megatrend perhaps more than any other company.

Incredibly, Amazon has another growth driver that may be even more powerful than its core online retail operations. Amazon Web Services has taken the world by storm, quickly becoming the dominant provider of scalable cloud computing services. AWS has a massive market opportunity -- so large, in fact, that Amazon's management believes it could eventually rival the company's retail operations in size. The business is already making progress in that regard, with AWS's third-quarter revenue surging 55% to $3.2 billion and operating income more than doubling to $861 million.  But AWS has just barely scratched the surface of its potential, and it should continue to turbocharge Amazon's revenue and profit growth for many years to come.

Exceptional management

Founder and CEO Jeff Bezos is relentless in strengthening Amazon's competitive position. Whether it's expanding the company's massive global distribution system to reduce shipping times, or investing heavily to bolster the content and service offerings of Amazon's fast-growing Prime membership service, Bezos is constantly working to deliver more value to Amazon's customers. He's proven time and again that he's willing to sacrifice short-term profits in order to maximize the long-term value of the business. That's served Amazon's shareholders well, and I expect it to continue to do so for many years to come.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.