Of all the chess books I have read my favourite is 'New Ideas in Chess' by Larry Evans, first published in 1958!
He expounds his chess theories of Pawn Structure, Force, Space and Time.
It is an easy read with lessons with diagrams set out on each page - open the book anywhere.
You can still get it for about three bucks!
My next favourite is 'Bobby Fischer: My 60 Memorable Games' with his inimitable annotations.
In another thread, Hugh_T_Patterson asked what the best book on the middlegame was. I'm not sure what the best one is, but here are a few that probably deserve consideration:
Aron Nimzowitsch. My System. - OK, so GM Kevin Spraggett doesn't like it. Even so, it covers a wide range of key topics: the two bishops, passed pawns, the seventh rank, pawn chains, doubled pawns, isolated pawns, attacking your opponent's pawn centre, etc. Quite clearly a classic and one of the most influential books on the middlegame.
Jeremy Silman. How to Reassess Your Chess. - Often recommended by North American chess trainers for intermediate players. Silman examines various imbalances (e.g. bishop vs knight) and what impact these have on planning.
John Watson. Secrets of Modern Chess Strategy. - Watson takes Nimzowitsch as a starting point, and argues that modern GMs try to exploit the specific peculiarities of each position even if it means ignoring general positional rules.
Vladimir Vukovic. The Art of Attack in Chess. - Vukovic tries to figure out under what conditions certain king hunt sacrifices will work.
Jose Raul Capablanca. Chess Fundamentals. - Explores clear moves for building up an advantage that can be exploited in the endgame.
Eugene Znosko-Borovsky. The Middlegame in Chess. - A lightweight book but fun to read.
Andrew Soltis. Pawn Structure Chess. - Tries to build a framework for deciding how to proceed based on the type of pawn structure.
Alexander Kotov. Think Like A Grandmaster. - Probably the first book to describe the ways in which grandmasters build up a tree of variations and evaluate the resulting positions to decide which move is best.
Emanuel Lasker. Lasker's Manual of Chess. - Obviously very old now, but it contains an excellent summary of Steinitz's ideas on the accumulation of small advantages, the necessity of attacking when you have the advantage and how to determine where to attack.
David Bronstein. Zurich International Chess Tournament 1953. - A games collection rather than an instructional book, but Bronstein offers plenty of fascinating insights into seizing the initiative, weak colour complexes and how to develop rapidly.
Are there other good books I have left out?