When a company manages to raise its dividend every year for decades, investors should take notice. A quarter-century of annual dividend hikes earns the title of Dividend Aristocrat, an exclusive club of a just few dozen companies. Out of those companies, three of our Fool contributors think Wal-Mart (NYSE:WMT), Medtronic (NYSE:MDT), and Nucor (NYSE:NUE) are the best buys. Here's why.

All-in on e-commerce

Tim Green (Wal-Mart): Retail behemoth Wal-Mart has increased its dividend every year since first declaring one in 1974. Dividend growth has been slow in recent years, with the current quarterly dividend of $0.50 per share representing just a 2% increase. But Wal-Mart is going through an important transition as it aggressively goes after the e-commerce market. These investments, along with higher wages and better training for its employees, are knocking down the company's profits.

Wal-Mart supercenter storefront

Image source: Wal-Mart.

Wal-Mart can no longer ignore the threat of Amazon.com and other online retailers. The company made a big move to acquire startup Jet.com last year, installing Jet CEO Marc Lore as the head of its entire e-commerce business. After toying with an Amazon Prime-like subscription service, Wal-Mart is now offering free two-day shipping on millions of items for orders above $35. Wal-Mart's e-commerce strategy is simple: Offer the best prices and fast, free shipping with no strings attached.

Analysts expect Wal-Mart to produce $4.33 in earnings per share both in 2016 and 2017, down considerably from a few years ago, reflecting the headwinds created by the company's investments. The payout ratio based on these estimates is about 46%, leaving Wal-Mart some room to continue raising the dividend even if earnings continue to languish. With a dividend yield of 3% and a management team that's thinking long-term, Wal-Mart is a Dividend Aristocrat worth considering.

The medical device king

Brian Feroldi (Medtronic): The world's population is aging, which is a terrific tailwind for the healthcare industry in general. As a leading provider of medical devices, Medtronic is a healthcare giant that looks well positioned to benefit from the trend.

Medtronic has grown into a behemoth thanks to its long history of expanding its treatments to address an ever-increasing range of diseases. While the company is likely best known for its pacemakers, Medtronic also sells devices that treat diabetes, treat neurovascular disease, assist with pain management, and more. This diversification makes Medtronic far more than just a one-trick pony.

Beyond product diversification, Medtronic has also made a lot of progress at getting its products into the hands of providers around the globe. Roughly 44% of the company's revenue comes from international markets, which adds yet another layer of diversification to its business.

When combined, these two factors have helped to ensure that the company's top and bottom lines move forward each and every year. That's one reason it has been able to increase its dividend for 39 consecutive years.

Looking ahead, I think that the company's current product lineup and its recently announced partnerships with Fitbit and Mazor Robotics provide investors with plenty of reasons to expect more of the same. That makes Medtronic a great Dividend Aristocrat to consider adding to your portfolio today. 

Betting on economic growth

Todd Campbell (Nucor): Nucor's shares are currently yielding 2.63%, management has increased the dividend every year for 44 straight years, and the stock is the biggest weighting in the Pro Shares S&P 500 Dividend Aristocrats ETF, but President Donald Trump is the real reason investors ought to stash this stock in their portfolios.

Trump won the fight for the U.S. presidency on his plans to reinvigorate the economy, and if his plans succeed, then U.S. steel demand could jump. On the campaign trail, Trump advocated for billions in new spending on projects that could benefit Nucor, the nation's biggest steel producer.

Nucor's products are used to construct highways, bridges, utilities, airports, and high-rise buildings, and that diversification makes this company a solid pick for investors trying to get exposure to GDP growth. If tariffs mean fewer steel imports, and demand for U.S. steel grows, then rising revenue could give management plenty of financial flexibility to increase dividends in the future.

As fellow Fool Dan Caplinger recently pointed out, Nucor sold 5.82 million tons of steel in Q4, up 14% year over year, and Nucor's revenue rose 14% to $3.96 billion. Clearly, this company's already got momentum heading into this year, and if that momentum builds because of Trump, then this stock is worth owning in dividend portfolios.

Brian Feroldi owns shares of AMZN and Mazor Robotics. Timothy Green has no position in any stocks mentioned. Todd Campbell owns shares of AMZN. The Motley Fool owns shares of and recommends AMZN and Fitbit. The Motley Fool owns shares of Medtronic. The Motley Fool recommends Nucor. The Motley Fool has a disclosure policy.