A Textual Commentary on the Greek New Testament by Bruce M. MetzgerTo be read alongside one's own NT, this "commentary" highlights and explains the major decisions and debates underneath modern NT critical editions. Helpful especially for those reading the NT in Greek (this commentary puts the apparatus into words), but accessible to all.
Junia: The First Woman Apostle by Eldon Jay EppThe name "Junia" appears in Romans 16:7, which was changed to a masculine form. Tracks how this happened in New Testament manuscripts, scribal traditions, and translations of the Bible.
The Living Text of the Gospels by D. C. ParkerAn accessible introduction to textual criticism in action. The author brings text criticism of the gospels to life and demonstrates the modern-day importance of the discipline.
The Orthodox Corruption of Scripture by Bart D. EhrmanAn accessible, and at times cantankerous, approach to NT text criticism that intertwines the discipline to the theological and social history of the earliest Christians.