Investors interested in stocks from the Aerospace - Defense sector have probably already heard of Embraer (ERJ Quick QuoteERJ - Free Report) and Northrop Grumman (NOC Quick QuoteNOC - Free Report) . 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 proven Zacks Rank emphasizes companies with positive estimate revision trends, and our Style Scores highlight stocks with specific traits.

Right now, both Embraer and Northrop Grumman are sporting a Zacks Rank of # 2 (Buy). This system places an emphasis on companies that have seen positive earnings estimate revisions, so investors should feel comfortable knowing that these stocks have improving earnings outlooks. However, value investors will care about much more than just this.

Value investors also tend to look at a number of traditional, tried-and-true figures to help them find stocks 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.

ERJ currently has a forward P/E ratio of 19.17, while NOC has a forward P/E of 21.57. We also note that ERJ has a PEG ratio of 1.13. This popular metric is similar to the widely-known P/E ratio, with the difference being that the PEG ratio also takes into account the company's expected earnings growth rate. NOC currently has a PEG ratio of 5.82.

Another notable valuation metric for ERJ is its P/B ratio of 0.93. The P/B ratio pits a stock's market value against its book value, which is defined as total assets minus total liabilities. For comparison, NOC has a P/B of 4.78.

These are just a few of the metrics contributing to ERJ's Value grade of A and NOC's Value grade of C.

Both ERJ and NOC are impressive stocks with solid earnings outlooks, but based on these valuation figures, we feel that ERJ is the superior value option right now.