Like, for me, Spivak's Calculus and Hubbard and Hubbard's Linear Algebra + Multivariable Calculus literally gave me wings. I began visualising problems in terms of matrices and transformations. Later I read Jaynes Probability Theory with much more ease. Because I got into thinking mathematically.
https://discrete.openmathbooks.org/dmoi3/
No left as exercise bullshit, no prove yourself bullshit, etc. Everything is explained thoughtfully and multiple times in the book, to ensure the readers really get the idea of the subject.
Also anything from Raymond Smullyan (logic musings/riddles).