Intuitive Surgical (NASDAQ:ISRG) and Medtronic (NYSE:MDT) aren't competitors. But they soon will be. Medtronic plans to launch a rival robotic surgical system to Intuitive Surgical's da Vinci system next year. 

When it comes to competing for investors' applause, it hasn't been much of a contest so far in 2017. Intuitive Surgical stock is up around 70%, while Medtronic stock has gained less than 10%. But which of these stocks is the better pick now? Here are the investing arguments for both medical-device stocks.

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The case for Intuitive Surgical

It's hard to beat Intuitive Surgical's business model. The company sells its da Vinci systems for between $500,000 and $2.5 million each, depending on the configuration. Customers buy service contracts for $80,000 to $170,000 per year. And then the customers spend $700 to $3,500 per procedure performed with da Vinci for instruments and accessories. Put all of that together, and Intuitive Surgical makes 71% of its money from recurring revenue sources

Once a hospital buys a da Vinci system, it has plenty of motivation to get a return on its investment. That means performing as many procedures using the system as possible. That, of course, means Intuitive Surgical makes even more money.

Intuitive Surgical stands to benefit tremendously from the aging of baby boomers. As this generation ages, it should mean more procedures performed using da Vinci, particularly radical prostatectomies. The company should also reap rewards from millennial women when they reach their early 40s, the average age range for hysterectomies -- currently the most-performed procedure for da Vinci. 

Aside from these demographic tailwinds, Intuitive Surgical has a couple of other great growth opportunities. One is international expansion. Almost two-thirds of da Vinci systems are installed in the U.S., but the U.S. makes up only 4% of the world's population. The company also has significant potential in applying da Vinci to new types of procedures.  

The case for Medtronic

Probably the two strongest arguments for investing in Medtronic stock are the company's dominance in the medical-device industry and its diversification of products. As for dominance, Medtronic is the largest medical-technology company in the world, with revenue of roughly $30 billion over the past 12 months.

Research firm Evaluate estimates that Medtronic has 7.7% share of the global med-tech market, well ahead of runner-up Johnson & Johnson, which has a market share of 6.5%. Medtronic also invests more in research and development than any of its peers, which bodes well for maintaining its leadership position in the industry.

What about diversification? Medtronic develops and markets products across four areas: cardiology, minimally invasive therapies, restorative therapies, and diabetes management. It claims the top spot globally in cardiology revenue and ranks fourth in restorative orthopedics revenue. 

In addition, Medtronic offers a plus for investors that Intuitive Surgical doesn't -- a dividend. The company's dividend currently yields a healthy 2.38%. Medtronic is a member of the elite group of Dividend Aristocrats and has increased its dividend for 40 consecutive years.

Better buy

If you're an income-seeking investor, Medtronic is definitely the better choice. If you focus primarily on value, Medtronic is probably more up your alley, also. The stock trades at 15 times expected earnings, compared with Intuitive Surgical's forward earnings multiple of 39.

That leaves growth investors. If you're in this category, go with Intuitive Surgical. The company's growth should pick up somewhat in the next few years compared with its recent history. Wall Street projects annual earnings growth of around 11%, which seems attainable, in my view. 

My favorite between these two stocks is Intuitive Surgical. I really like its long-term growth prospects. Its high valuation isn't of tremendous concern to me, because that's normal for Intuitive. I also think the company will be able to maintain its dominance even with increased competition, because of its huge head start and extensive track record of success in robotic surgery. Both stocks would make good additions to a investment portfolio, in my view, but I give the edge to Intuitive Surgical.

Keith Speights has no position in any of the stocks mentioned. The Motley Fool owns shares of and recommends Intuitive Surgical and Johnson & Johnson. The Motley Fool owns shares of Medtronic. The Motley Fool has a disclosure policy.