Investors looking for stocks in the Utility - Electric Power sector might want to consider either AES (AES) or IdaCorp (IDA). But which of these two companies is the best option for those looking for undervalued stocks? Let's take a closer look.There are plenty of strategies for discovering value stocks, but we have found that pairing a strong Zacks Rank with an impressive grade in the Value category of our Style Scores system produces the best returns. The proven Zacks Rank puts an emphasis on earnings estimates and estimate revisions, while our Style Scores work to identify stocks with specific traits.Right now, AES is sporting a Zacks Rank of #2 (Buy), while IdaCorp has a Zacks Rank of #3 (Hold). Investors should feel comfortable knowing that AES likely has seen a stronger improvement to its earnings outlook than IDA has recently. 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.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.AES currently has a forward P/E ratio of 9.25, while IDA has a forward P/E of 19.92. We also note that AES has a PEG ratio of 1.08. 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. IDA currently has a PEG ratio of 7.97.Another notable valuation metric for AES is its P/B ratio of 1.68. Investors use the P/B ratio to look at a stock's market value versus its book value, which is defined as total assets minus total liabilities. By comparison, IDA has a P/B of 1.85.Based on these metrics and many more, AES holds a Value grade of A, while IDA has a Value grade of D.AES 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 AES 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 The AES Corporation (AES): Free Stock Analysis Report IDACORP, Inc. (IDA): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research