Firefox has been my go-to browser since I can't remember when. 2008 was when I got my first laptop, so maybe then, though I did browse on the desktop computers we had before that. Don't remember what I used, other than I did use Internet Explorer way back when, since I've been going on the internet since 1998
Eight years later, Firefox remains my favorite browser. I do have Chrome as a backup but outside of using it when I run into rare issues, I see little reason to switch because Firefox has all my stuff saved and remains a reliable browser.
On my iPhone I use Safari because I'm too lazy to change the default and Safari works fine for what little phone browsing I do.