Investors interested in stocks from the Internet - Software and Services sector have probably already heard of Criteo S.A. (CRTO) and Quotient Technology (QUOT). But which of these two stocks is more attractive to value investors? We'll need to take a closer look to find out.The best way to find great value stocks is to pair a strong Zacks Rank with an impressive 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, Criteo S.A. is sporting a Zacks Rank of #2 (Buy), while Quotient Technology has a Zacks Rank of #3 (Hold). This means that CRTO's earnings estimate revision activity has been more impressive, so investors should feel comfortable with its improving analyst outlook. 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.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.CRTO currently has a forward P/E ratio of 7.35, while QUOT has a forward P/E of 65.36. We also note that CRTO has a PEG ratio of 1.47. 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. QUOT currently has a PEG ratio of 4.51.Another notable valuation metric for CRTO is its P/B ratio of 1.19. 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, QUOT has a P/B of 3.06.These are just a few of the metrics contributing to CRTO's Value grade of A and QUOT's Value grade of F.CRTO has seen stronger estimate revision activity and sports more attractive valuation metrics than QUOT, so it seems like value investors will conclude that CRTO is the superior 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 Criteo S.A. (CRTO): Free Stock Analysis Report Quotient Technology Inc. (QUOT): Free Stock Analysis Report To read this article on Zacks.com click here.