Investors looking for stocks in the Utility - Gas Distribution sector might want to consider either MDU Resources (MDU) or New Jersey Resources (NJR). But which of these two companies is the best option for those looking for undervalued stocks? 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 proven Zacks Rank emphasizes companies with positive estimate revision trends, and our Style Scores highlight stocks with specific traits.Both MDU Resources and New Jersey Resources have a Zacks Rank of # 2 (Buy) right now. This means that both companies have witnessed positive earnings estimate revisions, so investors should feel comfortable knowing that both of these stocks have an improving earnings outlook. But this is just one factor that value investors are interested in.Value investors are also interested in a number of tried-and-true valuation metrics that help show when a company is undervalued at its current share price levels.Our Value category highlights undervalued companies by looking at a variety of key metrics, including the popular P/E ratio, as well as the P/S ratio, earnings yield, cash flow per share, and a variety of other fundamentals that have been used by value investors for years.MDU currently has a forward P/E ratio of 15.26, while NJR has a forward P/E of 25.54. We also note that MDU has a PEG ratio of 3.05. This metric is used similarly to the famous P/E ratio, but the PEG ratio also takes into account the stock's expected earnings growth rate. NJR currently has a PEG ratio of 4.26.Another notable valuation metric for MDU is its P/B ratio of 2.04. The P/B ratio pits a stock's market value against its book value, which is defined as total assets minus total liabilities. For comparison, NJR has a P/B of 2.31.These metrics, and several others, help MDU earn a Value grade of B, while NJR has been given a Value grade of F.Both MDU and NJR are impressive stocks with solid earnings outlooks, but based on these valuation figures, we feel that MDU is 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 MDU Resources Group, Inc. (MDU): Free Stock Analysis Report NewJersey Resources Corporation (NJR): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research