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.

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 rely on traditional forms of analysis on key valuation metrics to find stocks that they believe are undervalued, leaving room for profits.

Zacks has developed the innovative Style Scores system to highlight stocks with specific traits. For example, value investors will be interested in stocks with great grades in the "Value" category. When paired with a high Zacks Rank, "A" grades in the Value category are among the strongest value stocks on the market today.

One stock to keep an eye on is China Southern (ZNH Quick QuoteZNH - Free Report) . ZNH is currently sporting a Zacks Rank of #1 (Strong Buy), as well as an A grade for Value. The stock has a Forward P/E ratio of 6.55. This compares to its industry's average Forward P/E of 8.42. Over the past 52 weeks, ZNH's Forward P/E has been as high as 31.97 and as low as 5.81, with a median of 8.34.

Investors should also recognize that ZNH has a P/B ratio of 0.81. The P/B ratio is used to compare a stock's market value with its book value, which is defined as total assets minus total liabilities. ZNH's current P/B looks attractive when compared to its industry's average P/B of 2.24. Over the past year, ZNH's P/B has been as high as 1.41 and as low as 0.43, with a median of 0.70.

These are just a handful of the figures considered in China Southern'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 ZNH is an impressive value stock right now.