Investors interested in Consulting Services stocks are likely familiar with Information Services Group (III) and Gartner (IT). 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 emphasizes companies with positive estimate revision trends, and our Style Scores highlight stocks with specific traits.Both Information Services Group and Gartner have a Zacks Rank of # 2 (Buy) right now. This means that both companies have witnessed positive earnings estimate revisions, so investors should feel comfortable knowing that both of these stocks have an improving earnings outlook. However, value investors will care about much more than just this.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 grades stocks based on a number of key metrics, including the tried-and-true P/E ratio, the P/S ratio, earnings yield, and cash flow per share, as well as a variety of other fundamentals that value investors frequently use.III currently has a forward P/E ratio of 13.85, while IT has a forward P/E of 41.22. We also note that III has a PEG ratio of 0.99. 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. IT currently has a PEG ratio of 3.05.Another notable valuation metric for III is its P/B ratio of 1.80. 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, IT has a P/B of 14.30.These are just a few of the metrics contributing to III's Value grade of A and IT's Value grade of D.Both III and IT are impressive stocks with solid earnings outlooks, but based on these valuation figures, we feel that III 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 Information Services Group, Inc. (III): Free Stock Analysis Report Gartner, Inc. (IT): Free Stock Analysis Report To read this article on Zacks.com click here.