Reassess Your Chess (though a new version is coming out in April) it really helps explain things. People swear by My System and it has great material and the newer translations are easier to read but I think the material is more advanced.
Choice of books
Sort:
Which should be read 1st, Reassess Your Chess or The Amateur's Mind, does anyone know?
Which book should I study first: 'My System' or 'Reassess Your Chess'?