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.

Considering these trends, value investing is clearly one of the most preferred ways to find strong stocks in any type of 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 NRG Energy (NRG Quick QuoteNRG - Free Report) . NRG 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 7.59, which compares to its industry's average of 14.32. NRG's Forward P/E has been as high as 13.18 and as low as 7.31, with a median of 8.43, all within the past year.

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 prefered metric because revenue can't really be manipulated, so sales are often a truer performance indicator. NRG has a P/S ratio of 1.02. This compares to its industry's average P/S of 2.31.

These are only a few of the key metrics included in NRG Energy's strong Value grade, but they help show that the stock is likely undervalued right now. When factoring in the strength of its earnings outlook, NRG looks like an impressive value stock at the moment.