Investors interested in Medical - Dental Supplies stocks are likely familiar with Becton Dickinson (BDX) and Merit Medical (MMSI). But which of these two companies is the best option for those looking for undervalued stocks? Let's take a closer look.There are plenty of strategies for discovering value stocks, but we have found that pairing a strong Zacks Rank with an impressive grade in the Value category of our Style Scores system produces the best returns. The proven Zacks Rank puts an emphasis on earnings estimates and estimate revisions, while our Style Scores work to identify stocks with specific traits.Becton Dickinson and Merit Medical are sporting Zacks Ranks of #2 (Buy) and #3 (Hold), respectively, right now. The Zacks Rank favors stocks that have recently seen positive revisions to their earnings estimates, so investors should rest assured that BDX has 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.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.BDX currently has a forward P/E ratio of 20, while MMSI has a forward P/E of 32.85. We also note that BDX has a PEG ratio of 2.42. 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. MMSI currently has a PEG ratio of 2.59.Another notable valuation metric for BDX is its P/B ratio of 2.94. Investors use the P/B ratio to look at a stock's market value versus its book value, which is defined as total assets minus total liabilities. By comparison, MMSI has a P/B of 3.97.These are just a few of the metrics contributing to BDX's Value grade of B and MMSI's Value grade of C.BDX stands above MMSI thanks to its solid earnings outlook, and based on these valuation figures, we also feel that BDX is the superior value option right now. Infrastructure Stock Boom to Sweep America A massive push to rebuild the crumbling U.S. infrastructure will soon be underway. It’s bipartisan, urgent, and inevitable. Trillions will be spent. Fortunes will be made. The only question is “Will you get into the right stocks early when their growth potential is greatest?” Zacks has released a Special Report to help you do just that, and today it’s free. Discover 7 special companies that look to gain the most from construction and repair to roads, bridges, and buildings, plus cargo hauling and energy transformation on an almost unimaginable scale.Download FREE: How to Profit from Trillions on Spending for Infrastructure >>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 Becton, Dickinson and Company (BDX): Free Stock Analysis Report Merit Medical Systems, Inc. (MMSI): Free Stock Analysis Report To read this article on Zacks.com click here.