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.Looking at the history of these trends, perhaps none is more beloved than value investing. This strategy simply looks to identify companies that are being undervalued by the broader market. Value investors use tried-and-true metrics and fundamental analysis to find companies that they believe are undervalued at their current share price levels.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.Stewart Information Services (STC) is a stock many investors are watching right now. STC is currently holding a Zacks Rank of #1 (Strong Buy) and a Value grade of A.Value investors also frequently use the P/S ratio. This metric is found by dividing a stock's price with the company's revenue. This is a popular metric because sales are harder to manipulate on an income statement, so they are often considered a better performance indicator. STC has a P/S ratio of 0.6. This compares to its industry's average P/S of 1.04.Finally, investors will want to recognize that STC has a P/CF ratio of 5.61. This data point considers a firm's operating cash flow and is frequently used to find companies that are undervalued when considering their solid cash outlook. This stock's P/CF looks attractive against its industry's average P/CF of 5.71. Over the past 52 weeks, STC's P/CF has been as high as 8.32 and as low as 5.05, with a median of 6.42.The Hanover Insurance Group (THG) may be another strong Insurance - Property and Casualty stock to add to your shortlist. THG is a # 2 (Buy) stock with a Value grade of A.The Hanover Insurance Group is trading at a forward earnings multiple of 12.62 at the moment, with a PEG ratio of 1.53. This compares to its industry's average P/E of 30.23 and average PEG ratio of 3.30.Over the last 12 months, THG's P/E has been as high as 17.22, as low as 11.90, with a median of 13.72, and its PEG ratio has been as high as 2.80, as low as 1.53, with a median of 2.34.Furthermore, The Hanover Insurance Group holds a P/B ratio of 1.52 and its industry's price-to-book ratio is 1.37. THG's P/B has been as high as 1.68, as low as 1.31, with a median of 1.53 over the past 12 months.Value investors will likely look at more than just these metrics, but the above data helps show that Stewart Information Services and The Hanover Insurance Group are likely undervalued currently. And when considering the strength of its earnings outlook, STC and THG sticks out as one of the market's strongest value stocks. Zacks Names "Single Best Pick to Double" From thousands of stocks, 5 Zacks experts each have chosen their favorite to skyrocket +100% or more in months to come. From those 5, Director of Research Sheraz Mian hand-picks one to have the most explosive upside of all. As one investor put it, “curing and preventing hundreds of diseases…what should that market be worth?” This company could rival or surpass other recent Zacks’ Stocks Set to Double like Boston Beer Company which shot up +143.0% in little more than 9 months and NVIDIA which boomed +175.9% in one year.Free: See Our Top Stock and 4 Runners Up >>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 Stewart Information Services Corporation (STC): Free Stock Analysis Report The Hanover Insurance Group, Inc. (THG): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research