[giobox]

My memory might be way off base here, but I'm fairly sure Chrome Dev Tools were in a reasonable state by 2012. Screenshots from the time certainly suggest so. My experience is much the opposite, in that it was around 2012 or so that I probably stopped installing Firefox on my dev machines altogether.

That said, recent features in Firefox (Containers especially) have me much more interested again.

[Zarel]

I played around with Chrome in 2008 when it first came out in beta, and I remember finding Chrome Devtools an improvement over Firebug.

By the time the Firefox 4 betas were out, it was no contest; Firebug was very crashy (which, to be fair, it's hard for an extension to support a beta browser, but Chrome's dev and beta channels always had a reasonably stable devtools thanks to it being built-in).