In a post on Christmas resources a couple of years ago, I mentioned that the best books I'm aware of on the historicity of the infancy narratives are Craig Keener's 1999 commentary on Matthew and Darrell Bock's 1994 commentary on Luke. A couple of lengthy commentaries on Matthew came out this year from conservative scholars, Knox Chamblin and Grant Osborne. And an updated version of D.A. Carson's Matthew commentary came out. I've read through the sections on Matthew 1-2 in all three of them, and I didn't see anything that significantly advances the case for a traditional view of the infancy narratives. All three have some good material. Carson's commentary is especially good. (It was a while ago that I read through the infancy material in the earlier version of his commentary. From what I remember of the earlier one, I think the updated version isn't much different. There are some changes here and there, such as some discussion of more recent sources on the star of Bethlehem, but not much.) I would still recommend Keener's commentary as the best book on Matthew and Bock's as the best one on Luke.
Between those two, I consider Keener's the better one. (I prefer Matthew's material to Luke's, which is part of the reason why I prefer Keener. I think Keener's commentary is better even aside from my preference for Matthew, though.) Keener may be more interested in issues of historicity than most commentators because of his background in atheism. He either understands the relevant issues better than other scholars or expresses his understanding more effectively. He cites a larger number and variety of both ancient and modern sources. He understands the significance of hostile corroboration and often discusses it. He addresses the issues more deeply and from a larger variety of angles. He comes across as having read and thought about the issues more widely and deeply. He takes issues of historicity more seriously than the vast majority of people in the church today tend to, including scholars.
This year's Matthew commentaries were disappointing, and I'm not aware of any others due out soon that seem promising. There are some promising Luke commentaries on the way. I'm thinking mainly of Richard Bauckham's and Stanley Porter's. But I haven't seen a date for Bauckham's, and the last date I saw for Porter's was 2016. It looks like Keener's and Bock's will be the best for a while longer.