I swear this isn't a homework question. I read Goldhagen and Browning as an undergraduate years ago, but I'm curious about how the debate has developed since their work was released. I also would love a refresher on the exact nature of the original debate.
You can't do better than read chapter two ("The Decision-Making Process in Context") of Dan Stone's Histories of the Holocaust (2010), the latest major work on the historiography of the Holocaust, published by Oxford University Press.