I was also trying to find THE book that would best prepare me, but from my own experience preparing for the test, and from seeing reviews of several materials others used, it seems like most people use a wide variety of materials to prepare. A lot of people seem to use GRE prep books as well. I did and thought it helped quite a bit with math and verbal. Now my math score was pretty bad, but it was more because I ran out of time rather than not knowing how to work the problems. The best advice I got is to do timed tests. Do them over and over and over until you can finish everything within the time allotted.