Investors with an interest in Industrial Services stocks have likely encountered both Siemens AG (SIEGY) and W.W. Grainger (GWW) . But which of these two stocks presents investors with the better value opportunity right now? 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 earning ...