I'm finding Bullets and Bandages useful as a reference. And Run and Gun has good stuff Martial Arts Styles for example.
Run Faster adds more races(metavariants, changelings, shapeshifters, pixies X3) so Pirakos and Karl actually could have up to date stat blocks for 5e
Street Grimoire and Shadow Spells adds more magic stuff such as toxic spirits, blood magic and plague magic, and more adept powers, etc.
Assassin's Primer is useful too