I have become a collector of commentaries ever since my seminary days in the 1990s. As such, I am only going to recommend the best overall commentary for each book of the Bible on this site. If you are teaching/preaching through Revelation, I honestly think you will be hard pressed to find a more helpful resource than Duvall's commentary. No, it does not go into as great of depth as a number of commentaries you will find, but it makes Revelation manageable for just about anyone (and it does it in a straightforward verse-by-verse manner). The ideas for illustrating the text while teaching are quite good. Supplement this with Beale's shorter commentary offering on Revelation as well as Richard Bauckham's "The Theology of the Book of Revelation."