I'm all into the "switch firefox on again" and removed my chrome from my quicklaunch. It's fast as a browser should be, and I trust mozilla a lot more than google. Yet, webkit/blink powers today a lot more than google chrome. I think headless mode & nodejs(v8) integration (e.g. nwjs/electron) is still a major missing feature to call it "a browser build for 2017"
I'm not sure why "use the JS engine from Chrome" is a good requirement for a non-Chrome browser, or what do you mean by "nodejs(v8) integration"?