Investors interested in Medical - Dental Supplies stocks are likely familiar with AmerisourceBergen (ABC) and Align Technology (ALGN). But which of these two companies is the best option for those looking for undervalued stocks? 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 favors stocks with strong earnings estimate revision trends, and our Style Scores highlight companies with specific traits.Right now, AmerisourceBergen is sporting a Zacks Rank of #2 (Buy), while Align Technology has a Zacks Rank of #3 (Hold). This system places an emphasis on companies that have seen positive earnings estimate revisions, so investors should feel comfortable knowing that ABC 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 tend to look at a number of traditional, tried-and-true figures to help them find stocks that they believe are undervalued at their 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.ABC currently has a forward P/E ratio of 11.41, while ALGN has a forward P/E of 140.23. We also note that ABC has a PEG ratio of 1.53. 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. ALGN currently has a PEG ratio of 11.36.Another notable valuation metric for ABC is its P/B ratio of 4.92. 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, ALGN has a P/B of 8.75.These are just a few of the metrics contributing to ABC's Value grade of A and ALGN's Value grade of D.ABC stands above ALGN thanks to its solid earnings outlook, and based on these valuation figures, we also feel that ABC 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 AmerisourceBergen Corporation (ABC): Free Stock Analysis Report Align Technology, Inc. (ALGN): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research