Here at Zacks, we focus on our proven ranking system, which places an emphasis on earnings estimates and estimate revisions, to find winning stocks. But we also understand that investors develop their own strategies, so we are constantly looking at the latest trends in value, growth, and momentum to find strong companies for our readers.Of these, value investing is easily one of the most popular ways to find great stocks in any market environment. Value investors rely on traditional forms of analysis on key valuation metrics to find stocks that they believe are undervalued, leaving room for profits.Luckily, Zacks has developed its own Style Scores system in an effort to find stocks with specific traits. Value investors will be interested in the system's "Value" category. Stocks with both "A" grades in the Value category and high Zacks Ranks are among the strongest value stocks on the market right now.Herc Holdings (HRI) is a stock many investors are watching right now. HRI is currently sporting a Zacks Rank of #2 (Buy), as well as an A grade for Value.We also note that HRI holds a PEG ratio of 0.66. 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. HRI's PEG compares to its industry's average PEG of 0.90. Over the last 12 months, HRI's PEG has been as high as 25.28 and as low as 0.62, with a median of 8.65.Value investors also frequently use the P/S ratio. This metric is found by dividing a stock's price with the company's revenue. Some people prefer this metric because sales are harder to manipulate on an income statement. This means it could be a truer performance indicator. HRI has a P/S ratio of 1.62. This compares to its industry's average P/S of 2.02.These are only a few of the key metrics included in Herc Holdings's strong Value grade, but they help show that the stock is likely undervalued right now. When factoring in the strength of its earnings outlook, HRI looks like an impressive value stock at the moment.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 Herc Holdings Inc. (HRI): Free Stock Analysis Report To read this article on Zacks.com click here.