David,
Both men were products of their own time and place. Something that usually gets lost in the discussions. They were conducting combat operations in two separate theaters. You could even point to men like Gerstner, a contemporary, and see still another apologetic approach. I'm not suggesting trying to find common denominators in these approaches, but to realize that these men in various ways were and were not consistent with fundamental principles that were, in fact, common to all their beliefs.
In other words,, don't worry so much about studying the "controversy"--no, better to spen those energies studying your own Systematic Theology. Know what you believe, and why, and how it all fits together in non-contradictory fashion. You need to know the Faith you are defending before you can defend it well. Then, and alongside those studies, you can be sifting through the methodological offerings, asking yourself which approach fits best out front of the theology you are learning to profess.
These men were all attacking enemies of the gospel. They each had their share of successes, they each led platoons of followers who bought in to their methodologies, their battle plans. Obviously, if you have a basic plan that is successful by your definition, then you wish to see it propagated and used in other places. Not so you can brag and be famous (hopefully not, anyway), but so that the wider church benefits.
Believe it or not ALL the methods are at some level, self-conscious or not, presuppositional. The issue is, how self-aware and consistent are people in recognizing and conforming their higher-level beliefs and actions with their presuppositions. Not every apologist tried to build up a system from such an analysis. They simply went with what worked for them. Hence, Gerstner's classicalism or Schaeffer's eclecticism. But guys like Clark or VanTil felt free to critique what they saw as those less rigorous approaches, as well as one another. Obviously the critiques were not always given or taken impersonally.
The books these men wrote all came out of real-world life experience in which they were engaged in combat with unbelief. Those battles and those things they believed in gave shape to their works. You should read and study their writings with this understanding in mind. And not with the idea that from a study of methodology you will come away with a magic bullet for your own combat operations.