Income investors rely on the Dividend Aristocrats to provide them with reliable, growing dividend income. These stocks have all raised the amount they pay in dividends year in and year out for at least a quarter-century, and along the way, most of them have delivered not only steadily rising dividend payments but also share-price appreciation to boot.

Currently, about 50 companies make the Dividend Aristocrats list, with more likely to join its ranks. A few of them are especially deserving of attention as we move into the New Year. Below, you'll get a chance to learn more about ExxonMobil (NYSE:XOM), Dover (NYSE:DOV), and Stryker (NYSE:SYK) and why they should be on dividend investors' radar in 2018.

ExxonMobil faces big challenges

ExxonMobil has been the leader in the energy industry for years, and it also has a strong reputation for shareholder-friendly dividend payouts. For 35 years in a row, the energy giant has rewarded its investors with annual dividend increases, including its most recent 3% rise during the spring of 2017. With a current yield of 3.7%, ExxonMobil is one of the most attractive dividend stocks in the Dow Jones Industrials for those focused on current income.

However, many dividend investors are nervous about ExxonMobil right now. Weak oil prices have been a thorn in the side of countless energy companies throughout the sector, and ExxonMobil is far from the only major oil company that's currently paying more in dividends than it has earned over the past 12 months. Yet even more troubling is the fact that ExxonMobil hasn't been doing as good a job as its peers in replacing the oil and natural gas it produces with new reserves, and that threatens to create a downward production spiral that would make it impossible for the company to sustain dividends, let alone grow them. Rising oil prices in 2018 would potentially bail out the energy giant, but investors will want to watch closely to see if that works out the way the company clearly hopes it will.

Exxon and Mobil gas station platforms.

Image source: ExxonMobil.

Dover looks to break up

Dover isn't a company that most investors know well, but the industrial manufacturer has one of the best track records for dividend growth in the market. For 62 straight years, Dover has delivered rising payouts to its shareholders, including a 7% boost during the late summer months in 2017. A yield of just 1.9% doesn't put the company among the top-yielding dividend stocks among the Aristocrats, but the stock's 70% advance since late 2015 has played a role in depressing what has historically been a somewhat higher dividend yield.

Yet Dover is contemplating major changes to its business. After announcing in September that it would pursue strategic alternatives to separate its upstream energy business from the rest of the company, Dover said earlier this month that it would spin off its Wellsite segment into a separately traded public company by the end of the second quarter of 2018. Dover CEO Robert Livingston reassured investors that the continuing company will keep "consistently returning capital to our shareholders through dividends and share repurchases," but shareholders will have to watch closely to make sure that the company complies with the formal requirements to remain an Aristocrat after the spinoff takes effect.

Is Stryker poised to join the list?

Finally, Stryker just announced an 11% dividend increase, and that makes 2017 the 25th year in a row that the medical device maker has boosted its payout by most counts. Many income investors might wonder whether Stryker truly deserves to become a Dividend Aristocrat, especially given a yield of just 1.2%. Yet the Aristocrats don't have any minimum yield requirement, and so as long as the group that oversees the list doesn't see any other reasons to exclude the company, Stryker should join their ranks come 2018.

Stryker has seen solid fundamental performance lately that has helped give it the capacity to raise its dividends. During the third quarter, the medical device maker reported strong organic sales growth, with all three of its key segments contributing to a healthier top line. A recent product recall will hurt short-term profits, but Stryker remains optimistic about its future. If the company formally joins the Dividend Aristocrats as expected, then increased interest from investors could provide an additional boost.

Get the dividend income you need

If you like dividends, the Dividend Aristocrats are a great source of investment ideas. You still have to do your homework before simply buying an Aristocrat blind, though, and knowing key information about these and other dividend stock leaders is crucial to ensuring your long-term investing success.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.