Books I would recommend :
My System (Aron Nimzowitsch) : The book that improved my game the most, transformed me from a 1450-1500 player to 1650+. Not recommended for beginners, as you will have to put in a lot of hard work to fully understand the material. I look forward to reading the book a second time, as there were several concepts that I need to understand better.
Logical Chess Move by Move (Irving Chernev) : Recommended for beginners. Classic Grandmaster games fully annotated by the author, as the title suggests, move by move. Lots of repetition in the explanations, but I think it actually helps a lot.
Capablanca's Chess Fundamentals : Some great stuff on the endgame, which has made me realise how ignorant I was about so many things. Also recommended for beginners.