This is part of a larger project reviewing commentaries on each book of the Bible. Follow the links from that post for more information on the series, including explanations of what I mean by some of the terms and abbreviations in this post. You can see my annotated Amazon Listmania! list of Ephesians commentaries if you want a quick overview of what I think are the most important commentaries if you want that before looking more deeply at this more detailed review.
My top picks on Ephesians are Peter O'Brien's PNTC and Harold Hoehner's commentary published by Baker (not in a series). They happen to be the most recent commentaries on Ephesians, but I think they would be best even if some of the others I'll mention had been published later. O'Brien is the easiest to read of the best Ephesians commentaries. He uses Greek font. It annoys me to no end when someone transliterates the original language without using the original font at least in footnotes, unless the intended audience is exclusively popular level. O'Brien was forced to transliterate in the main text due to the format of the series, but he insisted on using real Greek text in the footnotes. That's ideal when a commentary's audience will include people with good Greek skills and people with no or not very good Greek. I can therefore recommend O'Brien to more people than some of the others in the list. I also think he exercises at least slightly better judgment about the basic meaning of the text than some of the others whose commentaries still qualify among the best. He's thoroughly mined all the major commentaries and has filtered out what's most crucial for interpreting the text accurately, but his exegesis and exposition derives directly from the text.
Hoehner has some of this as well. He offers more detail than O'Brien, though it's tougher going for those without good Greek skills. His focus is more on the words Paul uses, and O'Brien is stronger in overall grammatical issues of how the words fit together. O'Brien seems to me to be a little more theologically acute than Hoehner, and Hoehner focuses a little more on individual words and less on grammatical considerations, but both books are excellent guides to Paul's thought in this epistle. Hoehner's dispensationalism occasionally colors his remarks, as you might expect from anyone coming from a particular interpretive framework, but most of his commentary steers away from trying to be an apologetic for dispensationalism and simply examines the text. I should say the same about O'Brien's Reformed Anglican perspective. He doesn't see his commentary as a way to find Reformed thought behind every nuance the way some Calvinists have. When these issues arise, I think O'Brien is more often correct than Hoehner, but these issues aren't in the forefront most of the time, even in a theologically crucial book like Ephesians. That's a testament to the carefulness of both commentators, who each had access to the other's manuscript. Both cite each other frequently, most of the time favorably. Hoehner is more familiar with pre-modern commentaries than most Ephesians commentators, but his use of them is more for linguistic issues than for theology, which is unfortunate. One reason for my slight preference for O'Brien is that his approach seems a little more comprehensive. Hoehner is much more focused on the meanings of words with less attention to other matters, even if he acknowledges the dangers of word studies without issues of context. See the discussion below in the comments for more on this issue.