Of the most common approaches to apologetics, which is most effective?
The goal of apologetics is to persuasively defend Christianity against charges of falsehood, inconsistency, or credulity. It's an intellectual discipline that serves to bolster the faith of Christian believers and to aid the task of evangelism, but are some methods more effective than others?  
Five Views on Apologetics examines the "how-to" of apologetics, putting five prominent techniques under the microscope:

• Classical – represented by William Lane Craig
• Evidential – represented by Gary Habermas
• Cumulative Case – represented by Paul D. Feinberg
• Presuppositional – represented by John M. Frame
• Reformed Epistemology – represented by Kelly James Clark

Offering a forum for presentation, critique, and defense, this book allows the contributors for the different viewpoints to respond to the others. Your own informed conclusions can then guide you as you meet the questions of a needy world with the claims of the gospel.
The Counterpoints series presents a comparison and critique of scholarly views on topics important to Christians that are both fair-minded and respectful of the biblical text. Each volume is a one-stop reference that allows readers to evaluate the different positions on a specific issue and form their own, educated opinion.