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.

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 tried-and-true metrics and fundamental analysis to find companies that they believe are undervalued at their current share price levels.

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 company to watch right now is Walgreens Boots Alliance (WBA Quick QuoteWBA - Free Report) . WBA is currently holding a Zacks Rank of #2 (Buy) and a Value grade of A.

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 popular metric because sales are harder to manipulate on an income statement, so they are often considered a better performance indicator. WBA has a P/S ratio of 0.06. This compares to its industry's average P/S of 0.12.

These are only a few of the key metrics included in Walgreens Boots Alliance'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, WBA looks like an impressive value stock at the moment.