Speaking personally, I never <i>left</i> Firefox.<p>I've been using Mozilla code since the Netscape 7.X days (and tried to use NS6, but it was way too buggy.) I progressed from MS7 to the Mozilla Suite to Firefox, and have stayed there.<p>I have Chrome (and Opera, Safari, Midori, Konqueror, K-Meleon, D+, and a few other things including IE installed, but mostly to keep up on what others are doing. Firefox is what I use in production, and I currently run Aurora (which will be the next release when it gets out of beta.)<p>FF isn't the smallest or fastest browser on the machine I'm on at the moment (and old netbook) but is the most capable. FF, like other current browsers, makes assumptions about what you will run it on, and assumes a reasonably current machine with a reasonable CPU, GPU, and amount of RAM. I have another old machine I don't even <i>try</i> to run FF on.<p>My reasons are tied up in the architecture. FF uses the Gecko engine, like everything else Mozilla puts out. Aside from HTML, CSS, and JavaScript, Gecko interprets and renders XUL, an XML language for designing user interfaces. The look and feel of FF is determined by XUL, CSS, and widgets, and the browser is simply an instance of something Gecko renders.<p>This makes it possible to create themes that change what FF looks like, and extensions that modify and extend what it does, and that power is why I use it. My RSS reader, IRC client and several other things that would ordinarily be external programs are implemented in FF as extensions. Since the browser is always running when I'm at the computer, this make things very convenient.<p>Other browsers like Chrome added an extension capability, but they are pure JavaScript and limited by what the device API will let you do in JavaScript. Half of what I do in FF isn't <i>possible</i> in Chrome.<p>Chrome is a worthy browser, and I'm glad it's there, but it's not what I use. It invokes somewhat faster than FF, but page rendering is equivalent, and memory usage rises rapidly as you add extensions, so there's little difference between FF and Chrome in use. Faster invocation is a non-issue here: I start the browser when I sit down at the machine and simply leave it running, so a few extra seconds to invoke it isn't a concern. Too many people have the bad habit learned from IE of hopping in and out of the browser, and I just tell such folks "You're doing it wrong".<p>On my desktop booted into Windows, I run FF from a RAMdisk. The desktop still runs XP and has 4GB RAM, but 32 bit Windows can only use 3.2GB of it. I found a RAMdisk driver that can use the rest and have a 768MBR ramdrive seen as Z:. Firefox, its cache, and its profile all live there and FF is run from there. It's <i>quick</i>. (Batch files populate the ramdisk on start up, and store the contents back to HD on shutdown.) I don't believe I can <i>do</i> that with Chrome.