Static analysis, formatters, typed properties, enums, readonly classes, attributes, Pest or PHPUnit, mutation testing, there’s a lot to choose from.

• Which single tool or feature changed your day-to-day work the most?
• What did you adopt that turned out not to be worth the effort?
• How did you introduce it into an existing codebase without a huge rewrite?
• What would you add first to a legacy project today?

Examples with before and after (bugs caught, review time saved) help most.