Investors with an interest in Transportation - Services stocks have likely encountered both Echo Global Logistics (ECHO) and ZTO Express Cayman Inc. (ZTO). But which of these two stocks offers value investors a better bang for their buck right now? We'll need to take a closer look.Everyone has their own methods for finding great value opportunities, but our model includes pairing an impressive grade in the Value category of our Style Scores system with a strong Zacks Rank. The proven Zacks Rank emphasizes companies with positive estimate revision trends, and our Style Scores highlight stocks with specific traits.Currently, Echo Global Logistics has a Zacks Rank of #2 (Buy), while ZTO Express Cayman Inc. has a Zacks Rank of #3 (Hold). Investors should feel comfortable knowing that ECHO likely has seen a stronger improvement to its earnings outlook than ZTO has recently. But this is just one factor that value investors are interested in.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.The Style Score Value grade factors in a variety of key fundamental metrics, including the popular P/E ratio, P/S ratio, earnings yield, cash flow per share, and a number of other key stats that are commonly used by value investors.ECHO currently has a forward P/E ratio of 13.45, while ZTO has a forward P/E of 32.31. We also note that ECHO has a PEG ratio of 0.77. 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. ZTO currently has a PEG ratio of 2.55.Another notable valuation metric for ECHO is its P/B ratio of 1.86. The P/B ratio pits a stock's market value against its book value, which is defined as total assets minus total liabilities. For comparison, ZTO has a P/B of 2.57.Based on these metrics and many more, ECHO holds a Value grade of B, while ZTO has a Value grade of C.ECHO stands above ZTO thanks to its solid earnings outlook, and based on these valuation figures, we also feel that ECHO is the superior value option right now. Breakout Biotech Stocks with Triple-Digit Profit Potential The biotech sector is projected to surge beyond $775 billion by 2024 as scientists develop treatments for thousands of diseases. They’re also finding ways to edit the human genome to literally erase our vulnerability to these diseases. Zacks has just released Century of Biology: 7 Biotech Stocks to Buy Right Now to help investors profit from 7 stocks poised for outperformance. Our recent biotech recommendations have produced gains of +50%, +83% and +164% in as little as 2 months. The stocks in this report could perform even better.See these 7 breakthrough stocks 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 Echo Global Logistics, Inc. (ECHO): Free Stock Analysis Report ZTO Express Cayman Inc. (ZTO): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research