Best opening books?

"... [Fundamental Chess Openings by Paul van der Sterren] is not particularly suited for players who are just starting out. I would imagine players rated at least 1400-1500 would get the most benefit from this volume. ..." - FM Carsten Hansen (2009)

https://web.archive.org/web/20140626173432/http://www.chesscafe.com/text/hansen128.pdf

http://www.jeremysilman.com/shop/pc/FCO-Fundamental-Chess-Openings-76p3561.htm

http://www.gambitbooks.com/pdfs/FCO_Fundamental_Chess_Openings.pdf

I would strongly recommend examining the sample.

https://www.chess.com/article/view/how-to-start-out-in-chess

https://www.chess.com/blog/Natalia_Pogonina/book-review-quotjourney-to-the-chess-kingdomquot

http://www.gambitbooks.com/pdfs/A_Complete_Chess_Course.pdf

"... This book is the first volume in a series of manuals designed for players who are building the foundations of their chess knowledge. The reader will receive the necessary basic knowledge in six areas of the game - tactcs, positional play, strategy, the calculation of variations, the opening and the endgame. ... To make the book entertaining and varied, I have mixed up these different areas, ..." - GM Artur Yusupov

I like Marin's "A Spanish Repertoire for Black". every book should be like that. Another I like is "The Ruy Lopez Move by Move" by Neil McDonald. 

I have others, but those two are the ones I like most. Marin's "Beating the open Games" is also acceptable, but the Spanish one is the best book I have.

https://www.qualitychess.co.uk/ebooks/SpanishUpdate.pdf

Sadler's book on the QGD is quite good and fits this mold.