Investors interested in Aerospace - Defense stocks are likely familiar with Embraer (ERJ Quick QuoteERJ - Free Report) and Northrop Grumman (NOC Quick QuoteNOC - Free Report) . But which of these two stocks presents investors with the better value opportunity right now? Let's take a closer look.

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 is a proven strategy that targets companies with positive earnings estimate revision trends, while our Style Scores work to grade companies based on specific traits.

Embraer has a Zacks Rank of #1 (Strong Buy), while Northrop Grumman has a Zacks Rank of #3 (Hold) right now. Investors should feel comfortable knowing that ERJ likely has seen a stronger improvement to its earnings outlook than NOC has recently. But this is just one piece of the puzzle for value investors.

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.

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 17.79, while NOC has a forward P/E of 19.34. We also note that ERJ has a PEG ratio of 1.05. This popular figure is similar to the widely-used P/E ratio, but the PEG ratio also considers a company's expected EPS growth rate. NOC currently has a PEG ratio of 8.83.

Another notable valuation metric for ERJ is its P/B ratio of 0.62. 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, NOC has a P/B of 5.43.

These metrics, and several others, help ERJ earn a Value grade of A, while NOC has been given a Value grade of C.

ERJ stands above NOC thanks to its solid earnings outlook, and based on these valuation figures, we also feel that ERJ is the superior value option right now.