What's your favorite Opening book / Engine combo for engine versus engine matches and why? 2nd being that opening books lead to certain types of set positions such as Closed, Open, Semi-Open, Endgame, and not to mention Gambit, Tactical, Strategic, or Positional. How would you classify your favorite Opening book? If one were to build a Opening book to target Rybka's weaknesses, how would you go about creating it and how long do you think it would take you to do so?
On a side note, this sounds like it would be a good idea for a contest (Building a Opening book to exploit all of Rybka's weaknesses.)

I wonder who of the many book makers would win it? Just who could be the 1st achieve such a honor when paired up with any non Rykba engine and the such Opening book of their own making?