Investing, especially in the artificial intelligence (AI) field, is fraught with uncertainty. Some stocks have returned 1,000% or more in a relatively short time, while others with potentially promising growth prospects ended up losing money for investors.

Such possibilities make investing in just one AI stock too risky to consider. Since no rules limit the number of AI stocks that an average investor can own, no shareholders should consider such a strategy.

Nonetheless, investors can often find high-quality choices by pondering what stock they might choose if they could only buy one AI stock. After considering this question, Motley Fool contributors have ideas on the stock each of them would choose under such limitations.

Amazon is already one of the world's biggest companies; AI will make it one of the most profitable.

Jake Lerch (Amazon): My choice is Amazon (AMZN -2.83%).

The reason I would choose Amazon above many other AI-related stocks like Nvidia, Palantir, and CrowdStrike Holdings -- which I still think are excellent investments -- is that Amazon's massive reach will allow it to put AI-powered tools to work at scale, driving tremendous amounts of profit for the company.

For example, let's put Amazon's size into perspective. Over the last 12 months, the company generated about $638 billion in revenue. That ranks second among American companies, trailing only Walmart. Indeed, Amazon is so big that its total sales are roughly equal to those of Microsoft (MSFT -1.90%), Nvidia, Tesla, and Meta Platforms -- combined.

That's important because advances in AI are likely to drive enormous gains in productivity throughout the entire economy. Higher productivity means higher profits, and therefore, the companies with the highest amounts of revenue stand to benefit the most from these gains.

Amazon has invested -- and is continuing to invest -- tens of billions of dollars into AI infrastructure. And those investments are already paying off.

AMZN Operating Margin (Quarterly) data by YCharts

In its most recent quarter (for the three months ending on Dec. 31, 2024), Amazon's operating margin hit 11.3%, the highest in the company's history. Undeniably, much of the credit for the company's rising profitability goes to AI. Amazon now uses AI in numerous ways, including:

• Supply chain management via AI predictions of demand
• Warehouse automation, including AI robots
• AI-powered delivery planning
• AI-generated customer review summaries
• Personalized shopping recommendations based on AI analytics of browsing and purchase history

What's more, many of these tools become more effective as they scale, meaning that Amazon can hope to generate even more profit over time. That's great news for Amazon shareholders, and it's why Amazon is the company I would choose if I could only own one AI stock.

This stock may be the closest second-chance stock to Nvidia

Will Healy (Advanced Micro Devices): Investors have several excellent options when it comes to AI investing, but at this particular time and place, I choose AMD (AMD -2.92%).

At first glance, this choice may seem counterintuitive. AMD's MI325X AI accelerator may not be as advanced as Nvidia's Blackwell GPU. Moreover, it has significantly trailed Nvidia in revenue growth and stock performance. That underperformance has contributed to a significant decline in the semiconductor stock. Now, it sells at close to a 50% discount from its peak last March.

However, despite such challenges, conditions may soon begin to go AMD's way. For one, the DeepSeek breakthrough, which can run AI models on significantly less computing power, could stoke demand for AMD's lower-cost processors. The data center segment, which designs its AI accelerators, now accounts for about half of the company's revenue.

The company has other chip-related segments as well, and it should also benefit from its growing AI capabilities. AMD's client segment, which makes PC chips, has benefited from its technical lead over struggling PC giant Intel. Also, revenue declines have dramatically slowed in its embedded segment, and its long-suffering gaming segment should eventually recover from its cyclical downturn.

In 2024, AMD's revenue of $26 billion rose 13% compared to year-ago levels. Still, with Q4 revenue up 24%, the accelerating revenue growth should bode well for its stock performance.

Additionally, the factor that arguably makes AMD the choice for today is its valuation. Although its 2024 net income of $1.6 billion helped lead to a 116 P/E ratio, the prospects for improved profit growth have taken its forward P/E ratio down to 24. Few fast-growing AI stocks sell for such a low valuation, meaning that buying now could boost investor returns amid a recovery.

As mentioned before, investors should avoid owning one AI stock if possible. Still, if one wants a diversified AI-driven business at a reasonable price, AMD stock is an excellent option.

Microsoft's high floor makes it the surest bet to enjoy AI's long-term tailwinds

Justin Pope (Microsoft): Sometimes, swinging for a home run isn't necessary. If AI is as big a deal as it looks, investors don't need to overcomplicate the investing angle. Technology conglomerate Microsoft is already one of the world's most prominent companies, making it an easy winner for AI. Its consumer and enterprise software has dominated the computer market for decades, with a deeply embedded user base perfect for deploying AI features.

Then there's the cloud business. Azure is the world's second-largest cloud platform, and Microsoft's massive balance sheet and deep pockets make it a leading AI hyperscaler. Microsoft is spending billions of dollars building data centers to support global AI adoption. Analysts believe AI demand will fuel 22% annualized revenue growth in the worldwide cloud services market through 2030, pushing the market to over $2 trillion. It's a tremendous growth opportunity that will directly benefit Microsoft.

That's the meat and potatoes of today's AI opportunity. Like the internet, AI will probably lead to new markets and innovations. Investors can reasonably expect Microsoft to participate in emerging growth trends. For example, it's already researching quantum computing and recently announced a breakthrough in chip design. That's the beauty of Microsoft; you get a proven winner with a fantastic existing business, plus the upside of the company's future projects.

There will be smaller, emerging stocks that outperform Microsoft. However, you might have a winner for every few stocks that lose money. You will likely make money with Microsoft if you give the stock time. The company generates tens of billions of dollars of cash profits annually, pays a growing dividend, and has its fingerprints across the entire technology sector. Plus, it has a higher credit rating than the U.S. government.

Sometimes, a bird in hand is worth two in the bush. That's why Microsoft is the best AI stock to own.