Raabe, Paul R. Obadiah. The Anchor Bible. New York: Doubleday, 1996.
Even though the contributors to The Anchor Bible series are usually theologically liberal, Raabe is a conservative Lutheran. His insights on the structure of the book, parallels between Obadiah and other biblical texts, and date were detailed and insightful. Even though Raabe adopted the mid-ninth century date, I found his detailed documentation of data regarding the date was valuable for my conclusion in favor of the mid-sixth century date.
Niehaus, Jeffrey. “Obadiah.” In The Minor Prophets. Edited by Thomas Edward McComiskey. Grand Rapids: Baker, 1993.
Niehaus provides one of the best recent defenses of the mid-sixth century date. His comments on the text are also insightful. Though this commentary has a section of commentary that deals with the Hebrew text in detail, it also has an English-only exposition that is accessible to those who do not know Hebrew.
Finley, Thomas J. Joel, Amos, Obadiah. The Wycliffe Exegetical Commentary. Chicago: Moody, 1990.
This is a detailed commentary on the Hebrew text from a premillennial perspective. The comments are careful and insightful. I’ve repeatedly found help in this commentary over the years.
Timmer, Daniel C. Obadiah, Jonah and Micah. Tyndale Old Testament Commentary. Downers Grove, IL: InterVarsity, 2021.
This is a brief, accessible commentary on Obadiah. However, I found insights in this commentary, especially toward the end of the book, that I was not finding in other commentators. Timmer is one of those authors whose works are always worth purchasing.
Block, Daniel I. Obadiah. Zondervan Exegetical Commentary on the Old Testament. Grand Rapids: Zondervan, 2017.
This commentary focuses on discourse analysis, and I found it useful in relating sections to one another as well as illuminating the grammar of the verses on for which I consulted it.