I started on IE, just because I was young and naive. I believe this was back in 2003-2004, and Firefox was kind of an underground, indie project. (Wikipedia says: November 2004 was FF's initial release.) So, maybe in mid-2005 is when I started using Firefox, and I really liked it. I got all the sweet extensions, add-ons, whatever you want to call them, and eventually my Firefox window was a disgusting hodgepodge. I put up with it and used my add-ons occasionally. I tried Safari somewhere in there, I'm like 'meh'. Better than IE, but didn't stack up to Firefox, methinks. Anyway, I downloaded chrome pretty soon after it came out and I really liked it, I still use it to this day. The whole thing is cleaner, sleeker, and better presented than Firefox, and offers several features like the Omnibar, better tab options, and an option to almost make the tab into a whole program (for example, I have a Blockland forum application which is essentially the Blockland forums without the top bar, making it look like a regular program window. Pretty sweet.)
That is my pilgrimage from IE to Chrome.