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When buying Dividend Aristocrats, you are buying the creme de la creme of stocks out there. These are companies that have been paying a dividend -- and growing that payment -- since 1991. A lot has happened since then, and some of these companies have held onto dividend increase streaks for even longer than that. It's hard to argue against buying Dividend Aristocrats because they have displayed a remarkable consistency for long periods of time. At the same time, though, that doesn't mean every one of them is a buy today. Buying a great company can be a less-than-great investment if you pay a hefty premium. 

Looking across the landscape of Dividend Aristocrats, here are three that stand out as worth buying today: Emerson Electric (EMR -1.36%), ExxonMobil (XOM 0.01%), and Nucor (NUE -2.56%). All three have generated fantastic returns for shareholders over the long run. 

EMR Total Return Price Chart

EMR Total Return Price data by YCharts.

Also, their shares look to be selling at a price that looks pretty attractive. Here's why each looks so compelling today. 

I like Ike (and Emerson's dividend)

Emerson is in rare company when it comes to dividend payments. It has raised its dividend annually for 59 years -- that's all the way back in the Dwight D. Eisenhower administration! Over that time frame, the company's business has grown and diversified from its roots as an electric motor and fan manufacturer into a manufacturing giant with products ranging from its bread-and-butter power motors, climate technologies, industrial automation equipment, and more consumer-facing commercial and residential supplies.

As a global manufacturer, the company's results can waiver with the broader health of the global economy. With emerging market growth slowing and continued anemic growth in the more mature markets like Europe and the U.S., Emerson's results have left investors a little wanting as of late. That's probably why shares now trade for an enterprise value-to-EBITDA ratio of 9.9 times, a rate that is below the company's average valuation over the past 20 years. It's times like this that can make a great company into a great stock. Emerson's dividend yield was this high back in the depths of the Great Recession.

Emerson can't control the rate of global economic growth, but to help make up for tepid growth environment into which it sells, the company is looking to cut operating costs and improve returns on capital. If they come to fruition, then even weak growth shouldn't hamper it from continuing its dividend streak. 

A rare discount

It's rare for a company like ExxonMobil to sell for what you might consider cheap. Its business model of owning assets in every part of the oil and gas value chain means that it isn't nearly as affected by the ups and downs of oil prices. It also helps that its management is one of the best at investing in high-return projects, keeping them on time and on budget, and generating long-term value for shareholders. 

Thanks to the long decline in oil prices, though, we are in one of those uncommon periods where the company's stock is selling at a pretty decent discount compared to its historical average. Since there is some volatility in it its earnings power from commodity prices, the most consistent metric for comparing ExxonMobil's stock value over time is its price-to-tangible book value. Based on this metric, shares of ExxonMobil are trading well below the average over the past 20 years. 

XOM Price to Tangible Book Value Chart

XOM Price-to-Tangible Book Value data by YCharts.

When you add in its 33-year history of raising dividends and today's yield of 3.1%, shares of ExxonMobil look pretty tempting to buy and hang on for a very long time. 

A business as solid as steel

Manufacturing steel has been a common practice for well over 100 years. When Nucor jumped into the steelmaking business with its first mini mill back in 1969, it brought changes with it. First, it eschewed the traditional blast furnace steelmaking method, opting instead for the newer, more efficient electric arc furnace technology that allowed it to run smaller batches and use scrap steel as a feedstock rather than iron ore. These methods helped the company build the nation's largest steel manufacturer and remains one of the most solidly profitable steel manufacturers in the business while so many others have either succumbed to bankruptcy or have been limping along for years with poor performance. 

Over the past few years, Nucor and the rest of the steel industry have been grappling with a massive oversupply of steel from China. In fact, a recent international trade organization ruling said that China and five other countries were dumping steel in the U.S. at less than cost. This glut of cheap steel had taken a toll on Nucor's results, and it has kept its stock standing still for the past eight years. 

However, things are starting to look much better for the steel industry. That ruling on illegal dumping means that those countries' imports into the U.S. carry large import tariffs that will boost the sales price for Nucor's steel. This has led to a recent run-up in its stock price, but this could be the beginning of something even more as the company will start to see improving profits in the coming months. 

You may not be buying shares of Nucor at the bottom of the cycle, but rest assured that the company will likely continue its 42-year streak of increasing dividends. Today's 2.75% dividend yield is also a pretty good consolation prize for not timing the market perfectly.