Here at Zacks, our focus is on the proven Zacks Rank system, which emphasizes earnings estimates and estimate revisions to find great stocks. Nevertheless, we are always paying attention to the latest value, growth, and momentum trends to underscore strong picks.Of these, perhaps no stock market trend is more popular than value investing, which is a strategy that has proven to be successful in all sorts of market environments. Value investors use a variety of methods, including tried-and-true valuation metrics, to find these stocks.In addition to the Zacks Rank, investors looking for stocks with specific traits can utilize our Style Scores system. Of course, value investors will be most interested in the system's "Value" category. Stocks with "A" grades for Value and high Zacks Ranks are among the best value stocks available at any given moment.One stock to keep an eye on is Park Hotels & Resorts (PK). PK is currently sporting a Zacks Rank of #2 (Buy), as well as a Value grade of A. The stock is trading with P/E ratio of 6.45 right now. For comparison, its industry sports an average P/E of 14.49. Over the past 52 weeks, PK's Forward P/E has been as high as 14.42 and as low as 5.81, with a median of 7.58.Investors should also note that PK holds a PEG ratio of 0.66. This figure is similar to the commonly-used P/E ratio, with the PEG ratio also factoring in a company's expected earnings growth rate. PK's industry currently sports an average PEG of 1.88. Within the past year, PK's PEG has been as high as 0.83 and as low as 0.64, with a median of 0.70.We should also highlight that PK has a P/B ratio of 0.63. Investors use the P/B ratio to look at a stock's market value versus its book value, which is defined as total assets minus total liabilities. This stock's P/B looks solid versus its industry's average P/B of 1.65. Over the past 12 months, PK's P/B has been as high as 1.11 and as low as 0.58, with a median of 0.75.Finally, our model also underscores that PK has a P/CF ratio of 6.11. This metric focuses on a firm's operating cash flow and is often used to find stocks that are undervalued based on the strength of their cash outlook. This company's current P/CF looks solid when compared to its industry's average P/CF of 13.79. PK's P/CF has been as high as 16.19 and as low as -129.76, with a median of 7.48, all within the past year.Investors could also keep in mind Service Properties Trust (SVC), an REIT and Equity Trust - Other stock with a Zacks Rank of # 1 (Strong Buy) and Value grade of A.Additionally, Service Properties Trust has a P/B ratio of 1.14 while its industry's price-to-book ratio sits at 1.65. For SVC, this valuation metric has been as high as 1.35, as low as 0.56, with a median of 0.86 over the past year.These are just a handful of the figures considered in Park Hotels & Resorts and Service Properties Trust'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 PK and SVC is an impressive value stock right now. Is THIS the Ultimate New Clean Energy Source? (4 Ways to Profit) The world is increasingly focused on eliminating fossil fuels and ramping up use of renewable, clean energy sources. Hydrogen fuel cells, powered by the most abundant substance in the universe, could provide an unlimited amount of ultra-clean energy for multiple industries. Our urgent special report reveals 4 hydrogen stocks primed for big gains - plus our other top clean energy stocks. See Stocks NowWant 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 Park Hotels & Resorts Inc. (PK): Free Stock Analysis Report Service Properties Trust (SVC): Free Stock Analysis ReportTo read this article on Zacks.com click here.Zacks Investment Research