By developer, do you mean web developer?
I tried to use Chrome dev tools, and they were incredibly easy to pick up; however whenever I try to use Firefox dev tools, they feel embarrassingly awkward. Perhaps it's just the familiarity with the tools (and if so, I am very curious to hear whether you prefer Firefox dev tools over Chrome's), but have a nagging feeling that it's just an inferior developer tool.
It was delightful when auditing the experiences from a potential new client in Firefox Dev Tools the other day, and realizing that I could see, inline to the target DOM element, JS events tied to them while looking through the source. Saved me a good amount of time.
When I'm looking for pure-play performance auditing, Lighthouse integrated into Chrome's Dev Tools are an obvious win.
So yeah, each have their strengths and weaknesses.
Just tried that, and wow, that's really cool!
Mozilla is one of the few tech companies that care about the well-being of its users. In my opinion that is very special.