These are some the books that I’m currently reading or have read.
Mathematics
Algebra
Kenneth Hoffman, Ray Kunze - Linear Algebra
Nice introduction to linear algebra that doesn’t spend too much time with explicit basis
Nathan Jacobson - Basic Algebra 1
Great introductory book to algebra
Nathan Jacobson - Basic Algebra 2
Nice overview of several topics with various choices of what to check out
Serge Lang - Algebra
Really I only used it to learn homological algebra lol
Claudio Procesi - Lie Groups
Atiyah, MacDonald - Introduction to Commutative Algebra
Matsumura, Reid - Commutative ring theory
Hartshorne - Algebraic Geometry
Analysis
Munkres - Topology (at least till ch 4, ch 5&6 are cool too)
As long as a rough intuition of calculus is there, this book is suitable to read before real analysis
Walter Rudin - Principles of Mathematical Analysis (till ch 7)
Other than the second chapter which is overly dense with topological definitions, the others are great
Walter Rudin - Real and Complex Analysis
Nice exposition to measure theory and complex analysis from a more measure theoretic persepctive. Measure theory part (ch 1-9) is great as an intro and the complex analysis is good after you know the basics.
Walter Rudin - Functional analysis
Klenke - Probability Theory: A Comprehensive Course
Miranda - Algebraic curves and Riemann surfaces
Topology
Lee - Introduction to Smooth Manifolds
Joseph J. Rotman - An Introduction to Algebraic Topology
Bredon - Topology and geometry
Tammo tom Dieck - Algebraic Topology
Martelli - An Introduction to Geometric Topology
Number Theory
Neukirch - Algebraic Number Theory
First two chapters are quite nice, tho some commutative algebra experience would really help with going through the content, third chapter is cute while the class field therory is a rather unique approach that may not be the best, but still rather interesting
Silverman - Arithematic of Elliptic Curves
Koblitz - Introduction to Elliptic Curves and Modular Forms
Diamond, Shurman - A First Course in Modular Forms
Physics
Goldstein - Classical mechanics
Good book once you are comfortable with writing Lagrangians
Landau, Lifshitz - The Classical Theory of Fields
I’d highly recommend this book for anyone looking to learn Special Relativity (+ Relativistic Electromagnetism). However the General Relativity section is rather questionable since it just tensor wacking which I don’t really like.
John David Jackson - Classical electrodynamics
Charles W. Misner, John Archibald Wheeler, Kip Thorne - Gravitation
R. Shankar - Principles of quantum mechanics
Steven Weinberg - Quantum theory of fields. Foundations Volume 1