Am I the only one here who thinks that nothing can beat the Chrome debugger ? Nothing comes even close. It's a different story if you are just browsing, like the 95% or more of the internet consumers.
While it's true the firefox debugger is lacking in certain areas, it's also better than chrome in others. Debugging CSS animations is much easier in firefox, but firefox lacks a way to look at websocket packets. One thing I like about firefox is that its debugger is a just a React webapp : https://github.com/devtools-html/debugger.html . So it's fairly easy to add to it !
If you go to the devtools settings you can add a lot of cool tools to the main pane including a canvas debugger and some other useful stuff.