I respect people choosing products based on ideality, but I personally will just use what suits my demand/preference best.
When I first switched from IE to Firefox 1.5, it's because it has tabs. And I loved it more and more once I figured out how well-built it is and how powerful addons can be.
When Chrome firstly came, it was pretty bad in term of functionality. The extension system is weak (compared to what Firefox can offer at the time), it lack TONS of what I personally consider as "essential features" (font settings for different languages is a big one for me as a non-Latin character user, for example), so I continued to use Firefox.
But Chrome catched up very quickly. Today, the features of two browsers are basically on par in my user case, especially after Firefox switched to WebExt (which I think is the right direction, by the way). I started to use Chrome more and more due to some small details, like better sync experience etc. Again, purely personal choice based on my heavy use of both.
Another thing that pushed me away from Firefox is my personal experience in bug reporting. I'm not a software developer, but I do report bugs semi-frequently. I feel like I was treated better in Chromium project than Firefox's one. I have lots of unhappy experiences there (the one that I still can't get over is that they won't fix a video playback bug that affects all Win7 + nVidia GPU users [1]). I think in Chromium everytime you report a bug with clear repro steps, there will at least an employee (or volunteer? Not sure) that will attempt to repeat your steps and attach a screencat of that in 1-2 days. It feels good.