Recommended companion: "Microeconomic Theory" by Mas-Colell, Whinston & Green (for the math) + "Notes on the Theory of Choice" by Kreps (for the intuition).
For decades, David Kreps’ A Course in Microeconomic Theory has stood as a rigorous, foundational text for graduate students in economics. Unlike the more procedural approach of Varian or Mas-Colell, Whinston & Green (MWG), Kreps emphasizes choice theory, subjective probability, and the strategic underpinnings of markets with a distinctive, conversational yet mathematically precise style.
However, anyone who has worked through Kreps knows the challenge: They aren't just computational drills; they are extensions of the text designed to bridge you from consumer theory to advanced decision theory.