Definitely the book. I mean, if it weren't for the book there would be no Eclipse :P Also, the book has a LOT more stuff in it. The movie has so much left out it's not even funny. -snickers- Okay I guess it is >.>
the book it has alot more that i would have liked to have seen in the movie. However the movie is the best out of the 3 that are out it follows the book the best the others try to but don't do it as well as Eclipse did.