Investors with an interest in Electronics - Semiconductors stocks have likely encountered both Silicon Motion (SIMO) and Ambarella (AMBA). But which of these two stocks is more attractive to value investors? We'll need to take a closer look to find out.The best way to find great value stocks is to pair a strong Zacks Rank with an impressive grade in the Value category of our Style Scores system. The Zacks Rank favors stocks with strong earnings estimate revision trends, and our Style Scores highlight companies with specific traits.Currently, Silicon Motion has a Zacks Rank of #2 (Buy), while Ambarella has a Zacks Rank of #5 (Strong Sell). Investors should feel comfortable knowing that SIMO likely has seen a stronger improvement to its earnings outlook than AMBA has recently. But this is only part of the picture for value investors.Value investors also try to analyze a wide range of traditional figures and metrics to help determine whether a company is undervalued at its current share price levels.Our Value category grades stocks based on a number of key metrics, including the tried-and-true P/E ratio, the P/S ratio, earnings yield, and cash flow per share, as well as a variety of other fundamentals that value investors frequently use.SIMO currently has a forward P/E ratio of 8.82, while AMBA has a forward P/E of 47.66. We also note that SIMO has a PEG ratio of 0.98. 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. AMBA currently has a PEG ratio of 3.18.Another notable valuation metric for SIMO is its P/B ratio of 3.69. The P/B is a method of comparing a stock's market value to its book value, which is defined as total assets minus total liabilities. By comparison, AMBA has a P/B of 6.06.These are just a few of the metrics contributing to SIMO's Value grade of B and AMBA's Value grade of F.SIMO has seen stronger estimate revision activity and sports more attractive valuation metrics than AMBA, so it seems like value investors will conclude that SIMO is the superior option right now. Infrastructure Stock Boom to Sweep America A massive push to rebuild the crumbling U.S. infrastructure will soon be underway. It’s bipartisan, urgent, and inevitable. Trillions will be spent. Fortunes will be made. The only question is “Will you get into the right stocks early when their growth potential is greatest?” Zacks has released a Special Report to help you do just that, and today it’s free. Discover 5 special companies that look to gain the most from construction and repair to roads, bridges, and buildings, plus cargo hauling and energy transformation on an almost unimaginable scale.Download FREE: How to Profit from Trillions on Spending for Infrastructure >>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 Silicon Motion Technology Corporation (SIMO): Free Stock Analysis Report Ambarella, Inc. (AMBA): Free Stock Analysis Report To read this article on Zacks.com click here.