I use Firefox as my main browser (but I'm a Linux user, so I'm already away from mainstream). (edit: tree-style-tabs is the killer feature/extension, and I can never go back)

I do still pop open chrome for the devtools when I'm working on web stuff. I wish I didn't have to, but there's one thing that FF doesnt have that I need at work: goto line in the sources browser.

Lots of our files at work are several thousand lines (I know...), and its a huge missing feature to me.

I might see if I can code it up myself and submit a patch, but that's not exactly trivial.