Everyone has their own ideas on what they like and find effective. Here are my choices on best books
100 Endgame You Must Know has 300 exercises with solutions that refer back to the original textbook.
10 chapters on basic topics with good exercises. Excellent explanations on topics that I thought I knew
Crucial Chess Skills for the Club Player vols 1+2
Excellent examples with good practical advice. Vol 2(40 exercises) was great and I just started vol 1(30 exercises)
Kamsky is a fanatic at analyzing and explaining his games. 22 games in this volume.
Some book you have to have and this is one of them
Dismantling the Sicilian
A bit old but very detailed with nice illustrative games. I don’t play 1.e4 but still this is an interesting book that summarizes a big chunk of theory into one book
The Chigorin Bible
Sokolov covered the plans with classical games and Salgado Lopez did the theory section