While the proven Zacks Rank places an emphasis on earnings estimates and estimate revisions to find strong stocks, we also know that investors tend to develop their own individual strategies. With this in mind, we are always looking at value, growth, and momentum trends to discover great companies.

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 a variety of methods, including tried-and-true valuation metrics, to find these stocks.

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.

One stock to keep an eye on is Tsakos Energy Navigation (TNP Quick QuoteTNP - Free Report) . TNP is currently sporting a Zacks Rank of #1 (Strong Buy) and an A for Value. The stock is trading with a P/E ratio of 3.38, which compares to its industry's average of 3.93. Over the last 12 months, TNP's Forward P/E has been as high as 6.40 and as low as -1.96, with a median of 3.87.

Value investors also love the P/S ratio, which is calculated by simply dividing a stock's price with the company's sales. This is a prefered metric because revenue can't really be manipulated, so sales are often a truer performance indicator. TNP has a P/S ratio of 0.44. This compares to its industry's average P/S of 1.23.

If you're looking for another solid Transportation - Shipping value stock, take a look at ZIM Integrated Shipping Services (ZIM Quick QuoteZIM - Free Report) . ZIM is a # 2 (Buy) stock with a Value score of A.

Additionally, ZIM Integrated Shipping Services has a P/B ratio of 1.44 while its industry's price-to-book ratio sits at 1.25. For ZIM, this valuation metric has been as high as 4.06, as low as 1.18, with a median of 1.79 over the past year.

These are only a few of the key metrics included in Tsakos Energy Navigation and ZIM Integrated Shipping Services strong Value grade, but they help show that the stocks are likely undervalued right now. When factoring in the strength of its earnings outlook, TNP and ZIM look like an impressive value stock at the moment.