Investors looking for stocks in the Banks - Foreign sector might want to consider either Santander Mexico (BSMX) or Toronto-Dominion Bank (TD). But which of these two stocks presents investors with the better value opportunity right now? Let's take a closer look.We have found that the best way to discover great value opportunities is to pair a strong Zacks Rank with a great grade in the Value category of our Style Scores system. The proven Zacks Rank emphasizes companies with positive estimate revision trends, and our Style Scores highlight stocks with specific traits.Santander Mexico has a Zacks Rank of #2 (Buy), while Toronto-Dominion Bank has a Zacks Rank of #3 (Hold) right now. Investors should feel comfortable knowing that BSMX likely has seen a stronger improvement to its earnings outlook than TD has recently. However, value investors will care about much more than just this.Value investors are also interested in a number of tried-and-true valuation metrics that help show when a company is undervalued at its 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.BSMX currently has a forward P/E ratio of 6.63, while TD has a forward P/E of 10.13. We also note that BSMX has a PEG ratio of 0.72. This metric is used similarly to the famous P/E ratio, but the PEG ratio also takes into account the stock's expected earnings growth rate. TD currently has a PEG ratio of 1.46.Another notable valuation metric for BSMX is its P/B ratio of 0.94. Investors use the P/B ratio to look at a stock's market value versus its book value, which is defined as total assets minus total liabilities. By comparison, TD has a P/B of 1.58.These are just a few of the metrics contributing to BSMX's Value grade of B and TD's Value grade of C.BSMX has seen stronger estimate revision activity and sports more attractive valuation metrics than TD, so it seems like value investors will conclude that BSMX is the superior option right now. Zacks' Top Picks to Cash in on Electric Vehicles Big money has already been made in the Electric Vehicle (EV) industry. But, the EV revolution has not hit full throttle yet. There is a lot of money to be made as the next push for future technologies ramps up. Zacks’ Special Report reveals 5 picks investorsSee 5 EV Stocks With Extreme Upside Potential >>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 Grupo Financiero Santander Mexico S.A. B. de C.V. (BSMX): Free Stock Analysis Report Toronto Dominion Bank The (TD): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research