The proven Zacks Rank system focuses on earnings estimates and estimate revisions to find winning stocks. Nevertheless, we know that our readers all have their own perspectives, so we are always looking at the latest trends in value, growth, and momentum to find strong picks.Of these, value investing is easily one of the most popular ways to find great stocks in any market environment. Value investors use tried-and-true metrics and fundamental analysis to find companies that they believe are undervalued at their current share price levels.On top of the Zacks Rank, investors can also look at our innovative Style Scores system to find stocks with specific traits. For example, value investors will want to focus on the "Value" category. Stocks with high Zacks Ranks and "A" grades for Value will be some of the highest-quality value stocks on the market today.Spirit (SAVE) is a stock many investors are watching right now. SAVE is currently sporting a Zacks Rank of #1 (Strong Buy) and an A for Value. The stock is trading with P/E ratio of 8.22 right now. For comparison, its industry sports an average P/E of 9.90. Over the past year, SAVE's Forward P/E has been as high as 9.41 and as low as 6.19, with a median of 8.SAVE is also sporting a PEG ratio of 0.50. This popular figure is similar to the widely-used P/E ratio, but the PEG ratio also considers a company's expected EPS growth rate. SAVE's PEG compares to its industry's average PEG of 0.70. Within the past year, SAVE's PEG has been as high as 0.50 and as low as 0.25, with a median of 0.37.Another valuation metric that we should highlight is SAVE's P/B ratio of 1.35. The P/B ratio pits a stock's market value against its book value, which is defined as total assets minus total liabilities. This company's current P/B looks solid when compared to its industry's average P/B of 2.63. Over the past 12 months, SAVE's P/B has been as high as 2.21 and as low as 1.04, with a median of 1.33.Finally, we should also recognize that SAVE has a P/CF ratio of 5.37. This metric takes into account a company's operating cash flow and can be used to find stocks that are undervalued based on their solid cash outlook. This stock's P/CF looks attractive against its industry's average P/CF of 5.88. Over the past 52 weeks, SAVE's P/CF has been as high as 12.55 and as low as 4.01, with a median of 5.14.These are just a handful of the figures considered in Spirit's great Value grade. Still, they help show that the stock is likely being undervalued at the moment. Add this to the strength of its earnings outlook, and we can clearly see that SAVE is an impressive value stock 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 To read this article on Zacks.com click here.