As I am (for CH601 Ancient Church, this fall) then I heartily recommend Michael Holmes’ (third) edition of The Apostolic Fathers. We don’t have it in the bookstore yet (it only occurred to me today to ask them—I’ll let you know when they come in. This is an excellent collection. The introductions are helpful, clear, and up-to-date. The text is well bound and cleanly printed with Greek and English on facing pages. Unlike the older (Lightfoot) edition I’ve had for years, this volume is printed like my Greek NT. It’s compact but easy to read.