Investors interested in stocks from the Engineering - R and D Services sector have probably already heard of Aecom Technology (ACM) and Altair Engineering (ALTR). 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 Zacks Rank favors stocks with strong earnings estimate revision trends, and our Style Scores highlight companies with specific traits.Currently, Aecom Technology has a Zacks Rank of #2 (Buy), while Altair Engineering has a Zacks Rank of #4 (Sell). Investors should feel comfortable knowing that ACM likely has seen a stronger improvement to its earnings outlook than ALTR has recently. But this is just one piece of the puzzle for value investors.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 Value category of the Style Scores system identifies undervalued companies by looking at a number of key metrics. These include the long-favored P/E ratio, P/S ratio, earnings yield, cash flow per share, and a variety of other fundamentals that help us determine a company's fair value.ACM currently has a forward P/E ratio of 20.15, while ALTR has a forward P/E of 64.42. We also note that ACM has a PEG ratio of 1.38. 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. ALTR currently has a PEG ratio of 5.37.Another notable valuation metric for ACM is its P/B ratio of 3.82. 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, ALTR has a P/B of 6.61.These metrics, and several others, help ACM earn a Value grade of B, while ALTR has been given a Value grade of F.ACM is currently sporting an improving earnings outlook, which makes it stick out in our Zacks Rank model. And, based on the above valuation metrics, we feel that ACM is likely the superior value option right now. FREE Report: The Metaverse is Exploding! Don’t You Want to Cash In? Rising gas prices. The war in Ukraine. America's recession. Inflation. It's no wonder why the metaverse is so popular and growing every day. Becoming Spider Man and fighting Darth Vader is infinitely more appealing than spending over $5 per gallon at the pump. And that appeal is why the metaverse can provide such massive gains for investors. But do you know where to look? Do you know which metaverse stocks to buy and which to avoid? In a new FREE report from Zacks' leading stock specialist, we reveal how you could profit from the internet’s next evolution. Even though the popularity of the metaverse is spreading like wildfire, investors like you can still get in on the ground floor and cash in. Don't miss your chance to get your piece of this innovative $30 trillion opportunity - FREE.>>Yes, I want to know the top metaverse stocks for 2022>>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 AECOM (ACM): Free Stock Analysis Report Altair Engineering Inc. (ALTR): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research