Firefox dev tools are becoming better and better. I disabled Firebug a few weeks ago, I don't miss it.
I agree that the dev tools are a lot better, and I've recently removed Firebug as well, but I've spent many months annoyed at Firefox dev tools appearing when I've wanted to inspect an element using Firebug. Firebug has been a resource hog for a long time now, but I feel that I stuck with it for longer than I should have because the Firefox dev tools were an annoyance.
Is there a specific reason why Mozilla didn't just ask the creator of Firebug if they could merge his work into the Firefox source, and build on the creators already good work.
Source: https://hacks.mozilla.org/2013/10/firefox-developer-tools-an...