Investors interested in Retail - Apparel and Shoes stocks are likely familiar with Tilly's (TLYS) and Stitch Fix (SFIX). But which of these two companies is the best option for those looking for undervalued stocks? Let's take a closer look.There are plenty of strategies for discovering value stocks, but we have found that pairing a strong Zacks Rank with an impressive grade in the Value category of our Style Scores system produces the best returns. The Zacks Rank favors stocks with strong earnings estimate revision trends, and our Style Scores highlight companies with specific traits.Right now, Tilly's is sporting a Zacks Rank of #2 (Buy), while Stitch Fix has a Zacks Rank of #3 (Hold). The Zacks Rank favors stocks that have recently seen positive revisions to their earnings estimates, so investors should rest assured that TLYS has an improving earnings outlook. However, value investors will care about much more than just this.Value investors analyze a variety of traditional, tried-and-true metrics to help find companies that they believe are undervalued at their current share price levels.Our Value category highlights undervalued companies by looking at a variety of key metrics, including the popular P/E ratio, as well as the P/S ratio, earnings yield, cash flow per share, and a variety of other fundamentals that have been used by value investors for years.TLYS currently has a forward P/E ratio of 12.36, while SFIX has a forward P/E of 873.90. We also note that TLYS has a PEG ratio of 1.12. This popular metric is similar to the widely-known P/E ratio, with the difference being that the PEG ratio also takes into account the company's expected earnings growth rate. SFIX currently has a PEG ratio of 29.13.Another notable valuation metric for TLYS is its P/B ratio of 1.74. 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. For comparison, SFIX has a P/B of 6.07.These metrics, and several others, help TLYS earn a Value grade of A, while SFIX has been given a Value grade of D.TLYS sticks out from SFIX in both our Zacks Rank and Style Scores models, so value investors will likely feel that TLYS is the better option right now.Want 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 Tilly's, Inc. (TLYS): Free Stock Analysis Report Stitch Fix, Inc. (SFIX): Free Stock Analysis Report To read this article on Zacks.com click here.