Veritas Prep Reading Comp:
This guide I think is the best book on RC you can buy. The book teaches you how to read each passage. How to approach RC in an effective and engaged manner. The book teaches you to read the passage so that you can answer all primary purpose questions without having to go back and read the passage. From there, the book describes the 6 RC question types you will encounter on the GMAT. The book also includes 90+ RC questions so you can practice the methods that you learned. The passages are really good and do a great job mimicking the logic and style that you will encounter on the GMAT.
Veritas Prep Critical Reasoning 1 and 2:
I think the real value of these guides is that they essentially teach you how to attack each Critical Reasoning question type and they present the material in a simplistic way. I think the main problem with the Power Score CR bible is that it is almost too much. I think these two guides provide you with all of the information you need to drastically improve your CR, but they present the material in a more manageable way.
Veritas Prep Advanced Word Problems:
I think this guide is a must have for anyone that wants to score a 49-51 on the GMAT. The book has 134 tough word problems, ranging from tough VICs problems to tough Combinatorics problems. This guide will throw almost anything that you would see on the GMAT at you. Going through this guide will just increase your comfort level with word problems.
Veritas Prep Problem Solving and Statistics:
This is the best guide for stats on the market. It goes above and beyond just teaching the minimum that you need for the gmat. The guide explains how to calculate standard deviations. Even though, the GMAT doesn't require you to know how to calculate this, I found it helpful because it really expands your understanding of the concept. This is very valuable for the DS stats problems where you have to attack them with a more conceptual approach. By having a more thorough understanding of stats, you can approach these stats problems with confidence. Additionally, this book is also a great resource for additional word problems. This book in conjunction with the Advanced Word Problems guide will provide a great base for attacking most of word problem that you will encounter on the exam.
Veritas Prep Data Sufficiency:
This book was very helpful for high lighting the tricks that GMAC uses in data sufficiency problems. The book teaches you what traps that you're looking for and how to approach DS problems so that you don't fall for one of the many traps that the test makers like to set. The book provides great practice and really gives you over 90 DS problems to practice identifying the traps that they teach you to look for.
Manhattan GMAT Number Properties:
I think this book does the best job for teaching number properties. It teaches everything from divisbility, exponents/roots, consecutive integers, and remainder theory. The advanced chapters of the book are difficult to understand but if you take the time to understand them, you will be positioned well to kill the math section.
Manhattan GMAT Equations Inequalities and VICs:
This book is great for learning how to attack inequalities, how to manipulate equations, and how to approach VICs problems. Each chapter has 15+ problems so you can make sure that you have a thorough understanding of each concept. I think these topics are some of the more difficult concepts on the math section and this book gives you the understanding that you need to attack any problem involving these concepts.
Manhattan GMAT Sentence Correction:
This guide is great teaching you all of the grammar that you need to learn for the GMAT. It is very thorough and even has advanced chapters that deal with the more difficult concepts. I think this book is a must have, the only thing I will say is that it doesn't really focus on word order or sentence structure, and you will have to have a great understanding of this in order to fully master Sentence Correction.