As a power user, I prefer Firefox to Chrome, due to its configurability and to the power of certain add-ons. One simple example: multi-row tab bar, thanks to custom CSS for the UI. It used to be even better before the mass murder of the now-called "legacy" extensions, but today we must settle for the less restricted offer.
As a developer, I don't typically use browsers as debuggers or programming environments, so I never experienced game-breaking differences.