While few and far between, some businesses are so strong that they can create wealth for generations. That's why we Fools think it's a worthwhile endeavor to constantly search the markets for great companies to buy.

So which companies have we found recently that we think are great buy-and-hold candidates? We asked a couple of investors to weigh in and they picked Johnson & Johnson (NYSE:JNJ) and Tucows (NASDAQ:TCX).

Rolled-up dollar bills stacked next to each other

Image source: Getty Images.

Stick with the winners

Demitri Kalogeropoulos (Johnson & Johnson): A major advantage of long-term stock-market investing is that it removes the pressure to find the next great revolutionary company. After all, an investor can accumulate massive capital gains over a long-enough time horizon simply by sticking with a business that has even a small operating advantage over its peers. The key is finding a company that's built to last for generations.

Johnson & Johnson is such a business. The healthcare titan has turned its dominance over dozens of niches across the pharmaceutical, medical-devices, and consumer-products industries into epic long-term growth. The share price has risen more than 2,200% over the last three decades, in fact.

The company's increasing reliance on pharmaceutical sales is producing more variability in its operations, which almost ensures the occasional year of disappointing annual results. However, few peers can come close to matching the $9 billion that Johnson & Johnson allocates toward research and development, and that focus on continually refreshed products should keep it at the forefront of the market over the coming decades.

Meanwhile, your returns are likely to be supercharged by dividend payments, especially if you chose to have them automatically reinvested, as the healthcare giant's dividend has continued climbing for 54 consecutive years.

A cash-cow business with a growth kicker

Brian Feroldi (Tucows): I'm a firm believer that a company needs to be capable of growing for decades in order to be considered a potential brag-worthy investment. For that reason, I think that Tucows is worth consideration.

Tucows is three businesses wrapped up in one. Let's take a closer look at each.

First, Tucows operates one of the largest internet-domain registration businesses on the planet. This predictable business makes up the lion's share of Tucows' revenue, allowing the company to crank out consistent profits. What's more, the recent acquisition of a competitor called Enom is helping to grow this business at a solid pace.

Second, Tucows operates a small but rapidly growing mobile service called Ting. Ting sets itself apart from national carriers by offering extremely low rates (the average customer bill is $23 per month) and providing superior customer service. With only 170,000 active subscribers, this business has a ridiculous amount of room left for future growth (for perspective, Verizon boasts 147 million subscribers).

Lastly, the company is investing its profits from the first two businesses to become a player in fiber internet. While the company only operates in a handful of cities at the moment, management has plans to rapidly add new towns in the coming years (occasionally from acquisitions).

When added together, Wall Street projects that these businesses will allow Tucows' profits to grow in excess of 29% annually over the next five years. Given the huge runway ahead for Ting mobile and internet, I could easily see this company maintaining an above-average growth for decades to come.