R.K. Harrison's WEC (1993) is a middle-range exegetical work, with an aim toward serving those who will teach the book of Numbers in Christian settings. Harrison's greatest strength is in historical background, but he is good on grammatical and theological matters as well. His views tend to be very conservative. I've seen some complaints that his focus doesn't always line up with the main concerns of the book itself. Unfortunately, this commentary is out-of-print and would need to be purchased used. [Full Review]