Fallen out of Love with FireFox
Been using it as my main browser Since 2003 when Blaster struck (Back on my Win98/XP Dual Booter), and until last year, I loved it.
Their push to kill XUL extensions before the WebExtentions API's were finished meant the six plugins I used to make the web work the way I wanted all stopped; spent the last two months trying to replicate the functionality with modern extensions, but it's just not possible (Protip; Not having a frikkin' toolbar API tells you everything you need to know about their attitude to portability, flexibility, and legacy)
So: If it looks like Chrome, serves ads like Chrome, and has less extensions than Chrome... why not just use Chrome?
Or even better, Palemoon or Waterfox, which is the decision I'm currently trying to make.