Investors interested in stocks from the Manufacturing - Electronics sector have probably already heard of Regal Beloit (RBC) and Eaton (ETN). But which of these two stocks presents investors with the better value opportunity right now? Let's take a closer look.We have found that the best way to discover great value opportunities is to pair a strong Zacks Rank with a great grade in the Value category of our Style Scores system. 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.Regal Beloit and Eaton are both sporting a Zacks Rank of # 2 (Buy) right now. This system places an emphasis on companies that have seen positive earnings estimate revisions, so investors should feel comfortable knowing that these stocks have improving earnings outlooks. 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.The Value category of the Style Scores system identifies undervalued companies by looking at a number of key metrics. These include the long-favored P/E ratio, P/S ratio, earnings yield, cash flow per share, and a variety of other fundamentals that help us determine a company's fair value.RBC currently has a forward P/E ratio of 19.86, while ETN has a forward P/E of 22.66. We also note that RBC has a PEG ratio of 1.99. This popular metric is similar to the widely-known P/E ratio, with the difference being that the PEG ratio also takes into account the company's expected earnings growth rate. ETN currently has a PEG ratio of 2.06.Another notable valuation metric for RBC is its P/B ratio of 2.12. The P/B is a method of comparing a stock's market value to its book value, which is defined as total assets minus total liabilities. By comparison, ETN has a P/B of 3.40.These are just a few of the metrics contributing to RBC's Value grade of B and ETN's Value grade of C.Both RBC and ETN are impressive stocks with solid earnings outlooks, but based on these valuation figures, we feel that RBC 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 Regal Beloit Corporation (RBC): Free Stock Analysis Report Eaton Corporation, PLC (ETN): Free Stock Analysis Report To read this article on Zacks.com click here.