The chapter on Romans in A Biblical-Theological Introduction to the New Testament: The Gospel Realized is helpful for understanding the structure of the book. The best, most comprehensive commentary is by Douglas Moo in the NICNT series (there is a 2nd edition available now). Shorter devotional commentaries we would recommend include The Message of Romans by John Stott and the volume in the Tyndale NT commentary series by F. F. Bruce. For more application driven readings, Nate has found Michael Bird’s commentary in the Story of God Bible series to be helpful. As always, if you prefer a good visual overview, watch the two Bible Project videos: https://youtu.be/ej_6dVdJSIU and https://youtu.be/0SVTl4Xa5fY
