The Adoration of Jenna Fox because it was genuinely gripping and had plot twists right up until the final page. While I suspected some things from the start (which I announced to my classes today), I didn't see many of the surprises coming. That is an awesome feeling.
Mary E. Pearson is such a smart woman, writing a story that appeals on so many different levels. My students probably won't follow the science, but will be staying up late to find out what secrets Jenna's parents are keeping from her. On the other hand, more mature readers will be impressed by the juxtaposition of Thoreau's Walden and ethical issues of biotechnology and what is 'real' and 'pure'. Lovers of bittersweet moments will revel in the final chapter, which had me closing the book slowly and saying "hmmm" in the best possible way.