I’ve written on commentaries before, such as here and here, and even here. I was just prompted by something I read to point out something else concerning commentaries. As well as the standard sage advice to not overly revere the commentaries, but rather treat them as conversation partners; as well as the solid suggestion to not invite them into the conversation too early; one more suggestion:
Don’t only read commentators that are solidly within your own theological tradition or denominational stream. It is tempting, especially with limited resources, to always buy from the same denominational publishing house, or in a series that is largely of your kind theologically. Some people seem to only read Reformed Calvinists, others look for well-known Arminian theologians, others like anything connected to Dallas, others want Abingdon Press, others only John MacArthur, others only Tom Wright, others only buy UK/Australian authors, etc. Tempting as such an approach may be, you will find that richer insight is gained by engaging with a variety of voices. All of these that I have mentioned can be helpful, as can Roman Catholic commentators, or Jewish commentators, etc.
A couple of caveats (since I know some readers will take me out of context and write me off theologically for one of the items in that list, or perhaps for all of them – I could list more until I find your favorite!) (1) Just because it’s different, doesn’t make it right, any more than it makes it wrong. That is to say, whatever their tradition or theology, some commentators deal with the text better than others – you are still looking for good commentators. (2) Make sure you have some grounding yourself before you bounce around in other camps. Reading multiple voices is part of good seminary training, but be careful not to intellectually buy into anything and everything in print. (3) Don’t neglect quality commentators from “your camp.” They will probably form the “spine” of your collection. (4) It is helpful to know where a commentator is coming from. It helps to know that this guy always looks for an obscure position and takes it. It helps to know that that one comes from a theology that tends to read these kinds of verses in this way.
Finally, I’ve mentioned John Glynn’s helpful book in the past. I’d like to point you to a very helpful online resource strongly influenced by John Glynn’s book. Perhaps you have not come across it yet – bestcommentaries.com. I would not say that I always agree with the scores given to a commentary, of course, but it largely seems to be a very helpful guide. Take a look around it, you will probably be glad to add it to your bookmarks!