Commentaries are meant to assist the reader in understanding a Biblical text by giving comments on the context and meaning of the text. The various contexts discussed may include the literary context, historical context, cultural context, and the language of the text. Modern commentaries will often discuss the text in a phrase by phrase or verse by verse manner. Most commentaries will have introductory material about the author, date, and composition of the book, as well as a discussion of themes and general outline of the book.
The series below are all active series. Each of them are adding new commentaries to their series. In some cases they are replacing older commentaries. We may, or may not have, all the titles available in a series. I also chose to not include one volume commentaries as they tend to not be as helpful as a single volume in a series.
As a rule, publishers have a bias. They books they choose to publish, or authors they ask to write for them are all based on that bias/leaning. So, in general here is a brief breakdown (this is by no means determinative, but may give you some hints):
Critical / Liberal: These commentaries tend to have a few things in common: reject or question traditional authorship of the book, read the book using higher criticisms, do not hold to inerrantist theology of inspiration and composition, and tend to read the text for the text, not for broader theological view, but broader cultural view. These commentaries may deny miracles and will tend to date things later than the conservative authors.
Augsburg/Fortress Press, Westminster/John Knox Press, and Random House/DoubleDay
Middle of the Road: Baker Books, Zondervan, Thomas/Nelson, Eerdmans, InterVarsity Press (IVP)
Conservative: These commentaries tend to have a few things in common: accept traditional authorship of the book, read the text in a more literal manner, hold to an inerrantist theology of inspiration and composition, and tend to read the text from a broader theological (often christiological/ecclesiological) stance.
Broadman & Holman
These commentaries will deal with the text from a translation and not from the original languages. Original languages will be mentioned, but are not the primary text used.
These commentaries will typically deal with text from their own translation and not from a standard translation. When dealing with the text itself they will either use the language in the proper fonts or use a transliteration (the word in Roman characters).