Investors looking for stocks in the Oil and Gas - Production and Pipelines sector might want to consider either Enbridge (ENB) or Williams Companies, Inc. (The) (WMB). But which of these two stocks presents investors with the better value opportunity right now? Let's take a closer look.Everyone has their own methods for finding great value opportunities, but our model includes pairing an impressive grade in the Value category of our Style Scores system with a strong Zacks Rank. The Zacks Rank is a proven strategy that targets companies with positive earnings estimate revision trends, while our Style Scores work to grade companies based on specific traits.Enbridge and Williams Companies, Inc. (The) are sporting Zacks Ranks of #2 (Buy) and #5 (Strong Sell), respectively, right now. This system places an emphasis on companies that have seen positive earnings estimate revisions, so investors should feel comfortable knowing that ENB is likely seeing its earnings outlook improve to a greater extent. But this is just one factor that value investors are interested in.Value investors also try to analyze a wide range of traditional figures and metrics to help determine whether a company is undervalued at its current share price levels.The Style Score Value grade factors in a variety of key fundamental metrics, including the popular P/E ratio, P/S ratio, earnings yield, cash flow per share, and a number of other key stats that are commonly used by value investors.ENB currently has a forward P/E ratio of 16.07, while WMB has a forward P/E of 35.17. We also note that ENB has a PEG ratio of 1.79. This popular figure is similar to the widely-used P/E ratio, but the PEG ratio also considers a company's expected EPS growth rate. WMB currently has a PEG ratio of 4.69.Another notable valuation metric for ENB is its P/B ratio of 1.23. The P/B ratio is used to compare a stock's market value with its book value, which is defined as total assets minus total liabilities. For comparison, WMB has a P/B of 1.48.Based on these metrics and many more, ENB holds a Value grade of B, while WMB has a Value grade of D.ENB is currently sporting an improving earnings outlook, which makes it stick out in our Zacks Rank model. And, based on the above valuation metrics, we feel that ENB is likely the superior value option right now.Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report Enbridge Inc (ENB): Free Stock Analysis Report Williams Companies, Inc. (The) (WMB): Free Stock Analysis Report To read this article on Zacks.com click here.