Suppose I only want to buy a single book for my opening repertoire as White and Black. Which book would you suggest?

 

I want something practical and I am not hoping for any magic. Just a good guide into a playable middlegame.

I know only one : The chess advantage in Black and White by L.Kaufmann 2004

it's however a thick book. Maybe Davies'dvd "opening for busy people" (or something close) would be more appropriate ?

Interesting! It was when reading about Kaufmann's book I got curious about other single volume repertoire books. I read a quote along the line that there exist other single volume repertoire books for those who seek a playable middlegame but that the Kaufmann book might aim for more.

Hoping to see many post on this subject.

i am cheapskate so i only spend money on the best of the best books.

While slightly outdated (and all opening books are outdated as soon as they are published), I suggest NCO (Nunn's Chess Openings.

I agree with Nimzovitch (of course) although NCO (1999) is NOT a "repetoire" book it's more like a one vol general opening manual. MCO-15 aint bad either although it's less encyclopedic but more up-to-date (2008). Having both books wouldn't be redundant or a waste of money IMHO.

You should also consider "Fundamental Chess Openings" by GM van der Sterren much less detailed than MCO or NCO but much more geared to explaining the concepts behind openings and their major variations.

You can read many customer reviews of all 3 (and many more books) at amazon, and also look around for used copies there

Good point,  NimzoRoy, that NCO is not a repertoire book.

A recommendation for such a book for gringubbe would partly depend on what type of game )open/closed, semi-) seeks.