My usage is now 99% Chrome, 1% Firefox (for testing purposes), and keep in mind I was one of those die-hard Firefox fans. I bought my Firefox t-shirt from the Mozilla store, installed it on school computers, supported it from the beginning and everything. Now I'm all Chrome and so is my whole family.
Looking back, the 3 main reasons why I loved Firefox was that was open source, which was emotionally appealing, its call-to-action was to end the tyranny of Internet Explorer, it was standards compliant, and it had extensions. Chrome now does those very same things, some much better than Firefox, and is catching up to the amount of useful extensions. And it looks and behaves better.
I will say this, Firefox has one thing that I really love over Chrome. When you set Firefox and Chrome to remember your last tabs open and load them on each startup, Firefox doesn't load all 80 tabs immediately I open it. Instead it only loads the currently selected tab and leaves the others unloaded, thus speading things up and preventing a system slowdown. Chrome on the other hand loads all 80 tabs at once, so I have to wait 15 seconds before the browser becomes responsive again.