So far, my favorite book has been A Storm of Swords. It contains several of my favorite (and most hated) moments throughout the entire series:

- The Red Wedding.

- Joffery dies. Finally.

- Tyrion kills Tywin.

- We meet Coldhands.

- Arya leaves for Bravos.

- Littlefinger absconds with Sansa.

- Daenerys becomes a real Queen.

- Catelyn becomes Zombie Catelyn.

- Samwell becomes the Sam the Slayer.

I enjoyed them all for different reasons. I guess if I had to pick I'd say a Storm of Swords is my favorite as well. It has the most STORY for sure. Can't wait to see it start to be tackled this season on HBO.