I choose the books which explain the concept more clearly and precisely. I like books which have many examples ranging from simple application to the real time applications of the concept. If I feel syllabus book is not sufficient than I will refer other local author which have in depth explanation having conceptual ideas
I go with the text books suggested in the syllabus book given to us and also class notes of friends and seniors. I take advice of lecturers of our college about which the books to study and what topics to cover from each book. If I feel that the book doesn't provide sufficient information about a topic and when it's indeed important, I will refer the Internet source like Wikipedia and others author book.