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 companies is the best option for those looking for undervalued stocks? Let's take a closer look.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 proven Zacks Rank puts an emphasis on earnings estimates and estimate revisions, while our Style Scores work to identify stocks with specific traits.Criteo S.A. and Quotient Technology 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 CRTO has an improving earnings outlook. However, value investors will care about much more than just this.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.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.CRTO currently has a forward P/E ratio of 8.60, while QUOT has a forward P/E of 73.56. We also note that CRTO has a PEG ratio of 1.72. 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. QUOT currently has a PEG ratio of 6.13.Another notable valuation metric for CRTO is its P/B ratio of 1.41. 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, QUOT has a P/B of 3.12.Based on these metrics and many more, CRTO holds a Value grade of A, while QUOT has a Value grade of D.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.