At work I use Firefox (mostly due to inertia) and Chrome, and IE sometimes whenever I need to debug a web site that's broken in IE.

At home I used to use Chrome on Windows and Safari on Mac. After I discovered the Personal Blocklist extension I completely switched to Chrome. Only that extension allows me to pretend that 4chan and Experts Exchange do not exist.

That's hardcore.

I use Iceweasel, which is essentially Firefox.

I should also mention I used to use Opera because it's jam packed with features, while still fairly fast. The add-ons and open-source nature of firefox won me over.

Google Chrome, easy and very fast!

I was Firefox from nearly its start, then adopted Chrome pretty seamlessly. After reading about IE9 on Ars Tech I just downloaded and am trying it out. IE has certainly come a long way.

I am using Internet Explorer 9 and it is enough for me.

Opera (and on my smartphone Opera Mobile) :)

IE 9 here, and I also like Chrome. I can't stand Firefox and never managed to consider it this godly browser everyone thinks it is.

I'm using Firefox 5.whatever and I really like it. I've been using Firefox for a long while now, and I am used to it (the new look in version 5 took a bit of getting used to, but I like it a lot more actually - I never really used the menu bar to begin with, so I like it not being there normally). I also am super attached to AdBlocker, it is the most godly thing. Recently I was using a computer in without it and I forgot how messy every single website looks with ads.

I'm using Opera but I am trying to find a different browser since the last updates have made Opera act weird with some weird slowdowns that summon the "(not responding)" text on the top of Opera for a few seconds.

Chrome.

Firefox

Opera. Has some great feature not requiring any plugins, like OperaMail, it launches fast, it works fast enough for me.

Nice search history and bookmarks tab.

I used to use IE until I started doing web development and discovered how awful it was with regard to standard compliance.

Now, I use mainly Firefox and sometimes Chrome for Flash heavy content.

I test my client-side logic on all 5 main browsers through (Safari, Opera, Chrome, Firefox, IE).

Chrome. Because it's fast.

Opera