Investors looking for stocks in the Outsourcing sector might want to consider either Atento (ATTO) or Automatic Data Processing (ADP). 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.Atento has a Zacks Rank of #2 (Buy), while Automatic Data Processing has a Zacks Rank of #3 (Hold) right now. This means that ATTO's earnings estimate revision activity has been more impressive, so investors should feel comfortable with its improving analyst outlook. But this is just one piece of the puzzle 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 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.ATTO currently has a forward P/E ratio of 15.79, while ADP has a forward P/E of 29.39. We also note that ATTO has a PEG ratio of 1.58. This figure is similar to the commonly-used P/E ratio, with the PEG ratio also factoring in a company's expected earnings growth rate. ADP currently has a PEG ratio of 2.26.Another notable valuation metric for ATTO is its P/B ratio of 0.96. 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, ADP has a P/B of 14.59.Based on these metrics and many more, ATTO holds a Value grade of A, while ADP has a Value grade of C.ATTO 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 ATTO is likely the superior value option right 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 To read this article on Zacks.com click here. Zacks Investment Research