Photo credit: Devon Energy Corp.

2015 will be a big year for America. That's the year we are expected to surge past Russia and Saudi Arabia and become the world's top oil producer. It's an amazing feat for a country that was thought to be running on empty. America is expected to remain the world's top oil producer at least through the end of the next decade. That long stretch of dominance presents a major opportunity for investors to buy American oil companies now. Below are what I believe are the three best oil and gas stocks to buy now.

Photo credit: Devon Energy Corp 

Growth at a great price
With an incredible position in some of North America's top energy resource plays, and a cheap valuation, Devon Energy Corp (DVN 0.75%) is a top oil stock to buy now.

What I like best about Devon Energy is its deep inventory of oil-rich growth opportunities. The inventory continues to grow as the company just bought a top-tier position in the Eagle Ford Shale. That added to its already strong position in the Permian Basin, world-class oil sands operations, and emerging position in several exciting new plays.

On top of all that the company is on rock-solid financial footing. It's living within its cash flow, yet still growing its oil production by 20% per year. Add to that its shareholder-friendly management team, which is buying back shares and increasing the dividend, and Devon Energy is one of the top American oil stocks out there these days.

Growth at a fair price
Another top oil and gas stock to buy is EOG Resources Inc (EOG 1.43%). The company just delivered a stellar quarter as it continues to thrive as a leader of America's oil boom. In my opinion it's just as good as Devon Energy and if anything, the only thing I don't love about EOG Resources is its price, as Devon Energy is cheaper. That said, EOG Resources holds top acreage positions in the three best horizontal oil plays in the U.S. Because of that it's expected to deliver best-in-class crude oil growth through at least 2017. In fact, EOG Resources is expected to grow to become America's top oil producer by 2018, which is impressive for a company that doesn't currently even rank in the top five.

In addition to holding positions in the top three oil plays, EOG Resources invests to keep its costs down while also delivering better wells each time it drills. Quite frankly, the profit potential makes it one of the best oil stocks in America as the company is simply printing money every time it drills a well.  

Amazing, untapped oil potential
Pioneer Natural Resources
(PXD 2.00%) estimates that it's sitting on 11 billion barrels of oil equivalent in future resource potential. To put that number into perspective, mighty ExxonMobil (XOM 1.26%) currently has 25 billion barrels of oil equivalent in proved reserves. While there is a big difference between proved reserves and resource potential in the oil industry, if even a portion of that oil and gas can be produced it would create a lot of value for Pioneer Natural Resources' investors. That's especially true when we consider the fact that ExxonMobil's market value is $413 billion while Pioneer Natural Resources' market value is just $28 billion. As the drilling program of Pioneer Natural Resources confirms its oil potential, the value of the stock will begin to reflect its more certain potential.

In addition to its resource potential, Pioneer Natural Resources offers investors a solid balance sheet and a growth program that's funded by its internally generated cash flows. Those cash flows should only improve over time as the company can now spend less on science as it focuses on development. That focus should begin to unleash the potential of its massive energy resources. Add it all up and Pioneer Natural Resources' potential alone makes it a very compelling oil stock to buy now.

Investor takeaway
There are a dozen or more oil and gas stocks that an investor could buy today. However, these are the three best oil stocks when weighing the potential reward with the risk it'll take to earn that reward. These three stocks are really leading the way in developing America's oil boom that has OPEC on notice.

One more oil stock that has OPEC worried about its future