The top cryptocurrencies have notched enormous gains over the last several years, but investors should be wary about expecting that momentum to continue. Crypto prices already look inflated, and even if these new types of digital currency continue to gain traction, there's not much to keep new coins with more advanced technology from disrupting the current batch of favorites.

Most people will probably be better served by putting their money into stocks rather than cryptocurrencies. With that in mind, we asked three of our Foolish investors to spotlight a company that could deliver better returns. Read on to see why they think that Intuitive Surgical (NASDAQ:ISRG), SunPower (NASDAQ:SPWR), and Activision Blizzard (NASDAQ:ATVI) are top cryptocurrency alternatives to consider. 

An illustration of a cryptocurrency token with a dollar sign on it.

Image source: Getty Images.

Going beyond what crypto can do

Dan Caplinger (Intuitive Surgical): Cryptocurrency promises to use technology to improve storing value, but there are other areas of the technology industry that will directly save lives and improve people's health. Intuitive Surgical has been on the cutting edge of robotic surgical systems for years, with its da Vinci system having played an instrumental role in boosting the number of surgical procedures that involve medical professionals using robotic tools. The precision that Intuitive Surgical's products allow surgeons to have in performing procedures has also led to use of the robotic surgical system in a wider array of surgeries, and that trend is likely to continue well into the future.

Competition is a threat that Intuitive Surgical faces, with companies large and small looking to introduce their own robotic systems to challenge the da Vinci system. Yet even as new systems come onto the market, the professionals who've developed expertise on Intuitive Surgical's products will likely be loath to switch to an untested, less familiar alternative. It'll likely take a new generation of medical professionals who haven't done their primary training on da Vinci systems to broaden out the market successfully. In the meantime, Intuitive Surgical will keep helping doctors save lives and improve the patient experience for those going through major surgical procedures.

A leader in energy's biggest growth segment

Travis Hoium (SunPower): If you're looking into cryptocurrencies, you may be interested in a high-risk but potentially very high-reward stock like SunPower. The solar manufacturer makes the industry's highest-efficiency solar panels and serves every market -- from rooftop solar customers to the largest project developers in the world. 

SunPower's bread and butter is residential and commercial projects, where its high-efficiency panels can squeeze more power from limited space. Not only has the company had success with that product, it's adding energy storage to the portfolio with an out-of-the-box solution for both markets. 

On the utility side of the business, SunPower is expanding production of its P-Series solar panel that takes commodity solar cells and assembles them like shingles to make panels that are slightly more efficient than competitors'. That's paired with design services, trackers, and other components in a turnkey solution called Oasis. It's P-Series that could ultimately drive SunPower to be one of the biggest solar manufacturers in the world

What's unnerved investors is SunPower's massive losses the last few years, but that's partly because it's clearing the balance sheet of project assets that are better served to be owned by utilities or other energy investors. Once that process is complete, the company will be almost net debt-free and will likely be profitable. With the potential for solar energy measured in the trillions of dollars, the possibilities for SunPower stock are astronomical. 

Still leveling up

Keith Noonan (Activision Blizzard): While cryptocurrencies might have more explosive upside potential, I think that investors will probably be better served by investing in growth stocks that have a sound fundamental backing. Activision Blizzard is a company that has a strong business and promising growth prospects, and I think that its stock is a long-term investment that will be able to deliver impressive returns.

Activision's video game business is booming. The company has a stable of franchise properties and development resources that are the envy of the industry and should allow it to capitalize on a growing market for interactive entertainment. Its console business is poised to continue benefiting from growth for full-game downloads and in-game purchases, and the company is still building out its mobile business, with plans to introduce advertising as a new sales generator and to bridge big franchises like Call of Duty to smartphones and tablets. An expanding global middle class and long-term growth opportunities in markets like China and India present more catalysts. Activision also looks poised to be a leader in growth areas like esports and mixed reality.

When it comes to introducing new hit properties, no game publisher has a better track record over the last decade, and the company is in the process of using its leadership position in gaming to build a more expansive multimedia empire. Activision is ramping up its original film and television development, with a Call of Duty movie universe already in the works and management expressing interest in a film or television series based on Overwatch. It's also making a bigger merchandizing push, a move that has the potential to strengthen a high-growth, high-margin revenue stream.

Activision Blizzard stock is priced for growth, trading at roughly 25 times forward earnings, but it's backed by a strong business that's primed to take advantage of favorable trends in its section of the entertainment industry. Like cryptocurrencies, I wouldn't classify the stock as low-risk, but I think it will ultimately deliver better results for most investors.