Investors with an interest in Technology Services stocks have likely encountered both Vontier Corporation (VNT) and Zeta Global Holdings Corp. (ZETA). But which of these two stocks offers value investors a better bang for their buck right now? We'll need to 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 proven Zacks Rank puts an emphasis on earnings estimates and estimate revisions, while our Style Scores work to identify stocks with specific traits.Vontier Corporation and Zeta Global Holdings Corp. are sporting Zacks Ranks of #1 (Strong Buy) and #3 (Hold), respectively, right now. This system places an emphasis on companies that have seen positive earnings estimate revisions, so investors should feel comfortable knowing that VNT is likely seeing its earnings outlook improve to a greater extent. But this is just one piece of the puzzle for value investors.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.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.VNT currently has a forward P/E ratio of 12.12, while ZETA has a forward P/E of 49.94. We also note that VNT has a PEG ratio of 1.56. 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. ZETA currently has a PEG ratio of 1.66.Another notable valuation metric for VNT is its P/B ratio of 16.60. The P/B ratio is used to compare a stock's market value with its book value, which is defined as total assets minus total liabilities. For comparison, ZETA has a P/B of 28.63.These metrics, and several others, help VNT earn a Value grade of B, while ZETA has been given a Value grade of F.VNT has seen stronger estimate revision activity and sports more attractive valuation metrics than ZETA, so it seems like value investors will conclude that VNT is the superior 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 Vontier Corporation (VNT): Free Stock Analysis Report Zeta Global Holdings Corp. (ZETA): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research