Historically, dividends are an enormous part of the long-term returns earned by investors. Now, eight years into a secular bull market, dividends might just be more important than ever. With this key insight in mind, we asked three Motley Fool contributors to share some of their best dividend picks for Foolish investors to consider in the second quarter. In response, they offered up HollyFrontier Corporation (NYSE:HFC), NextEra Energy Partners (NYSE:NEP), and National Retail Properties (NYSE:NNN). 

Read on for all the key details. 

A stock chart heading upwards through time.

Image source: Getty Images.

Shifting to higher value products

Sean O'Reilly (HollyFrontier Corporation): This independent petroleum refiner takes crude oil and turns it into everything from gasoline and jet fuel to even the asphalt found in one of the countless parking lots we use every day. While not as large as other refiners, or the integrated oil majors like ExxonMobil, HollyFrontier is still a force to be reckoned with as the owner of five refineries scattered across the Southwest, boasting a capacity to refine just under 500,000 barrels of crude oil every single day.

Based in Dallas, Texas, HollyFrontier has a great deal to offer dividend-minded investors on the hunt for yield in the second quarter. While the last few years have not been kind to the refiner, the future appears bright as the costs of its input (oil) and output (refined products) normalize. CEO George Damiris underscored this optimistic outlook in the company's first-quarter conference call:

We anticipate solid economic growth will continue to support refined product demand and sustained growth in domestic crude oil production will lead to improved crude differentials. We are also optimistic that a more favorable regulatory environment could provide a tailwind for both the refining industry and the economy as a whole. With a large portion of our scheduled maintenance behind us, we are poised for strong financial and operational performance for the remainder of the year.

Wall Street analysts are taking note, and ratcheting up forward earnings out through fiscal 2019:

 MetricFY 2017FY 2018FY 2019
Normalized earnings per share (estimated) $1.55 $2.52 $3.17

Data source: S&P Global Market Intelligence

The reason for this optimism isn't just the recovery in gasoline refining margins; it also has to do with a pivotal move made last year: the acquisition of Suncor Energy's Petro-Canada advanced products refining operations. This is a big deal -- it moves HollyFrontier away from being a simple oil refinery and closer to being a player in the increasingly important advanced petroleum products industry of the 21st century. With a dividend yield of 4.8%, and shares down some 50% from their lofty heights of a year ago, HollyFrontier has a great deal to offer forward-thinking investors in search of yield. 

A renewable dividend for 2017

Travis Hoium (NextEra Energy Partners): Energy dividends have long been a favorite of investors, but renewable energy dividends are still fairly new to the market. NextEra Energy Partners is arguably the industry's best renewable yieldco, which owns wind, solar, and other projects with long-term contracts to sell energy to utilities at set prices. 

The point of a yieldco is to provide a consistent dividend to investors; in NextEra's case, the current yield is 4.3%. And while there are higher dividends in the yieldco space, the low dividend yield is actually an advantage. The best way for a yieldco to grow is to issue shares and debt, and buy projects that have a higher rate of return than the cost of issued capital. The low dividend helps lower the cost of new equity. 

NextEra Energy Partners' dividend may not be the highest yield on the market, but management plans on growing it at 15% for years to come. If it's able to buy projects aggressively while its dividend is low, it may be able to lock in that dividend growth ahead of time.

A smarter way to play retail

Brian Feroldi (National Retail Properties): It is no secret that the retail industry is in a state of upheaval. The boom in e-commerce sales is putting the hurt on scores of established retailers and is pressuring sales. In turn, several prominent retailers have filed for bankruptcy while others have been forced to close waves of stores.

Given that backdrop, you might think I'm crazy for recommending National Retail Properties. After all, this REIT invests solely in retail properties that house a single tenant. You might think that this business model sets the company up for long-term failure given today's retail realities.

Here are a few reasons why I'm willing to take the other side of that bet.

First, National Retail Properties only rents to established tenants under long-term, net-lease contracts. When management say "long-term," they mean it. Most contracts start at 10 to 20 years long. In fact, the weighted average lease across its tenants is currently 11.6 years.

Next, the company's focus on "net-lease" terms also benefits investors. This means that the tenant is responsible for all variable property expenses such as maintenance, taxes, insurance, and utilities. National just gets to sit back and collect rent checks that are protected by those long-term contracts.

Finally, National primarily rents to retailers that are naturally immune to e-commerce sales. Its top tenants include convenience stores, restaurants, automotive service centers, and family entertainment centers.

Combined, these factors help National to maintain stellar occupancy rates. In fact, the company's current occupancy rate is 99%!

In total, National isn't your average retail REIT, which is why I think that investors can bank on the company's 27-year-long dividend increase streak continuing from here. With shares down 26% from their high and offering up a dividend yield of 4.6%, I think right now is a great time to get in.

Brian Feroldi has no position in any stocks mentioned. Sean O'Reilly has no position in any stocks mentioned. Travis Hoium has no position in any stocks mentioned. The Motley Fool owns shares of ExxonMobil. The Motley Fool has a disclosure policy.