<Classic> for a book means famous, not necessarily new. The first textbook of Quantum Mechanics is the 1930 1st Ed. of Dirac' Principles of Quantum Mechanics. It's definitely 'the classic', as can be considered von Neumann's 1932 book. These 2 were the first books on quantum mechanics *with Dirac focusing on principles and formalism, while the Hungarian von Neumann on the mathematical structure of the new (at that time) theory*.
Putting modern textbooks at the level of >classical< is a bold and not necessarily justified enterprise. Perhaps by 2050 we can call Weinberg's 2013 book on QM as classical.