I'll Give You the Sun has been my favorite right from the first round - I was so sad when it went down to The Night Gardener (though that's a great book, too) and was thrilled to see it re-emerge as Zombie pick.  It's been a long time since I read it now, so the details are getting a little fuzzy as they swirl around into a mural in my mind.  Although I really enjoyed both The Night Gardener and Nazi Hunters, and I think they would also be devoured by some kids, this is the one I haven't been able to get out of my head.  I've talked about it with friends and colleagues, bought it for kids in my life who I knew would love it, and shared little plot previews and teasers with students when I could.  This is my pick!