So far, probably the first Samwell chapter. The attack on the Fist of the First Men and its aftermath was super inticing and fun to read about, and at times I genuinely felt scared for the characters. Also, just generally awesome North-storyline writing from George R.R. Martin. And Sam is easily one of my favourite characters, so that was immediately a boost for the chapter. In the first two books, I liked the Wall-North storyline a tiny bit less than the main action in King's Landing and Winterfell and everywhere else, but this book for me has really brought that part of the story to the forefront and is making me like it even more. Also, giants!!!