I've been using Firefox since it was called Phoenix and was involved in my own little way in stripping out Netscape code once the fork was made. I've never moved from it since, and still find it to be a highly-performant and capable browser. I'm also okay for the most part with things like Sync and Pocket, even if I don't use them myself.
An open-source browser that often made decisions by mind-numbingly long message lists was never going to be able to compete with a company who realised that owning the engine and browser was their path to enormous profits and domination of the end-user experience for billions of people.
Mozilla is now a vassal of Google. That is not a good thing, but at least we still have a browser that offers us some level of control over the end-user experience.
The Internet has lost a lot of what made it exciting and new. The suits won.