For those seeking a mechanics book after K&K that covers Lagrangian and Hamiltonian mechanics, Taylor is recommended, although it has limited coverage of Hamiltonian mechanics. Other notable suggestions include Calkin, Gregory, and Greiner. Griffiths' Electrodynamics is highly regarded and suitable to follow Purcell, with some recommending concurrent study to maximize understanding before advancing to more complex texts like Jackson. Regarding Griffiths' Quantum Mechanics, opinions vary; while it is considered a solid resource, it is advised to focus on mastering analytical mechanics and electromagnetism first. Comparatively, Griffiths' problems are generally seen as slightly easier than those in Purcell, with some suggesting that while Griffiths presents more advanced material, the problem difficulty does not significantly increase. Additionally, alternative texts like Melvin Schwarz's "Principles of Electrodynamics" and Zangwill's E&M book are mentioned as valuable resources, with Zangwill noted for its pedagogical strength.