The NRSV Concordance, Unabridged - by John R. Kohlenberer III (Grand Rapids, MI: Zondervan, 1991).

The NRSV Concordance is the best choice for an English-only concordance of the entire Bible. For a New Testament concordance, the Word Study Greek English New Testament (WSGENT) would be the best choice. For the Old Testament concordance, the best choice would be The Hebrew-English Concordance to the Old Testament by John Kohlenberger & James Swanson (Grand Rapids, MI: Zondervan, 1998).