Which of these browsers do you use? What are your reasons for using this browser? If neither, which do you use and why?
Neither, I use Vivaldi because I like it.
I use all 3, but prefer the Chromium based browsers.
Firefox due to principles, manifesto.
I switched to Ice Dragon from Firefox because I was having display problems at some web pages. Also, Ice Dragon is so resource-light, and now, of course, it is under the Mozilla umbrella, which it wasn’t when I first downloaded it. I still like Firefox, & have it as my back-up browser. I will never use Chrome, just because I don’t like all my eggs in one basket - if you know what I mean. 
+1