Investors with an interest in Transportation - Services stocks have likely encountered both TFI International Inc. (TFII) and Grupo Aeroportuario del Pacifico (PAC). But which of these two stocks is more attractive to value investors? We'll need to take a closer look to find out.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 proven Zacks Rank emphasizes companies with positive estimate revision trends, and our Style Scores highlight stocks with specific traits.Right now, TFI International Inc. is sporting a Zacks Rank of #2 (Buy), while Grupo Aeroportuario del Pacifico 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 TFII has an improving earnings outlook. 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.TFII currently has a forward P/E ratio of 14.20, while PAC has a forward P/E of 18.52. We also note that TFII has a PEG ratio of 0.74. This popular figure is similar to the widely-used P/E ratio, but the PEG ratio also considers a company's expected EPS growth rate. PAC currently has a PEG ratio of 1.48.Another notable valuation metric for TFII is its P/B ratio of 3.85. 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, PAC has a P/B of 6.80.Based on these metrics and many more, TFII holds a Value grade of B, while PAC has a Value grade of D.TFII stands above PAC thanks to its solid earnings outlook, and based on these valuation figures, we also feel that TFII is the superior value option right now. Just Released: Zacks Top 10 Stocks for 2022 In addition to the investment ideas discussed above, would you like to know about our 10 top buy-and-hold tickers for the entirety of 2022? Last year's 2021 Zacks Top 10 Stocks portfolio returned gains as high as +147.7%. Now a brand-new portfolio has been handpicked from over 4,000 companies covered by the Zacks Rank. Don’t miss your chance to get in on these long-term buysAccess Zacks Top 10 Stocks for 2022 today >>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 TFI International Inc. (TFII): Free Stock Analysis Report Grupo Aeroportuario Del Pacifico, S.A. de C.V. (PAC): Free Stock Analysis Report To read this article on Zacks.com click here.