The best graph theory book I have seen thus far, and the only one I have seen where the subject feels connected rather than a collection of scattered results around a common theme. There are several choices the authors made that I believe help with this overall feeling of unity to the subject:
1. Introducing Ford-Fulkerson early and recalling it with future instantiations of the theorem (i.e. Menger's theorem, Edmonds' branching theorem, etc.).
2. The highly useful insets that show how the theory of combinatorics is largely built around methods and strategies, rather than algebraic theory.
3. Discussing chromatic polynomial, flow polynomial, and Tutte polynomials, which identify common patterns for graph invariants.