You've no doubt heard the old investment adage, "Sell in May and go away." The idea is to get out of stocks until later in the year when your chances of positive returns are better. Perhaps that strategy works at times, but I've always thought that the best time to buy shares of a great company with tremendous long-term growth prospects is always sooner rather than later.

The fact is, there are stocks with these characteristics that are strong picks right now. There's no need to wait months to invest in them. Actually, such a move could be counterproductive. While there are several stocks that I think are worth checking out, my top stock to buy in June is Intuitive Surgical (ISRG 0.50%).

Surgeons using a da Vinci robotic surgical system.

Image source: Intuitive Surgical.

A solid reopening play

My hunch is that buying Intuitive Surgical shares in June rather than waiting until autumn will pay off. Why? Because the company should benefit from the reopening of the economies in the U.S., Europe, and Asia.

Intuitive took it on the chin in 2020 with the COVID-19 pandemic. Hospitals delayed non-emergency surgical procedures as they at first braced for and then experienced a surge in COVID-19 cases. This caused the number of procedures performed with Intuitive's da Vinci robotic surgical systems to decline. And the company's revenue uncharacteristically fell as well.

ISRG Revenue (Quarterly) Chart

ISRG Revenue (Quarterly) data by YCharts

The worst appears to be over for Intuitive Surgical. However, CFO Marshall Mohr noted in the company's Q1 update that "resurgences of COVID-19 and its variants, like those currently being experienced in parts of Europe and the U.S., have challenged hospital care capabilities, and have negatively impacted da Vinci procedures." 

This negative impact should taper off as more people receive COVID-19 vaccines. Several drugmakers are already testing vaccine candidates that specifically target emerging coronavirus variants. It likely won't be long before Intuitive's business is fully back on its strong pre-pandemic growth track.

Thinking long-term

Even if Intuitive Surgical wasn't a strong reopening play, I'd still view the stock as a good one to buy in June. As my Motley Fool colleague Alex Carchidi recently pointed out, Intuitive is an "evergreen stock." In other words, pretty much any time is a good time to buy the stock.

The main reason why that's the case is that Intuitive Surgical's long-term growth prospects are outstanding. In 2020, more than 1.2 million procedures were performing using the company's robotic surgical systems, up slightly from the prior year despite the pandemic. Intuitive estimates that there are around 6 million procedures performed each year for which it already has products and regulatory clearances. 

There's even better news, though. Roughly 20 million soft tissue surgical procedures are performed annually that are ideal candidates for robotic assistance. Intuitive continues to develop new technological innovations that will enable it to target this even larger market opportunity.

Remember that those numbers reflect what's in place today. Aging demographic trends across the world will drive increased demand for many of the surgical procedures for which Intuitive's systems are used for years to come.

One noteworthy challenge

Throughout most of the more than two decades that Intuitive Surgical has been in business, it had the robotic surgical systems market to itself. That's no longer the case.

Large rivals such as Johnson & Johnson and Medtronic now offer surgical robots. Smaller companies including Asensus Surgical (formerly known as TransEnterix) are also vying for market share. Some potential rivals don't directly compete against Intuitive yet. However, without question, Intuitive faces more competition than it ever has.

Can Intuitive meet this challenge? I think so. The company has a huge head start with a large install base. Existing customers have financial incentives to maximize their return on investment with their da Vinci systems. They also clearly like Intuitive Surgical. The company enjoys a net promoter score (NPS), which measures customer loyalty, at the top end of the range of NPS scores categorized as "excellent."

New customers should continue to be attracted to Intuitive Surgical as well. The company's track record is unsurpassed. Its training programs and other resources offered to customers are also key pluses. And Intuitive continues to invest in innovation so that it stays at the top of the industry.

My view is that the robotic surgical systems market is and will remain big enough to support multiple winners. However, I'm confident that Intuitive Surgical will be the biggest winner of all over the long run. This healthcare stock is in a league of its own.