Modern browsers are really awesome, I use my Firefox to organise, store and read research papers, manage calenders, listen to radio, run codes in IPython notebooks and so on. In short, if there was some way i could embed my terminal and emacs inside firefox window, firefox will become a complete OS!!
At the same time, I dislike privacy infringing addons and tools which take away data or information from my machine, so I take some extra effort to make sure all the addons are free softwares and try to understand what data they send to their servers.
Paradox is that, more you try to customise your browser for privacy, more unique your browser's fingerprint becomes. Browser's fingerprint is all the capabilities and configurations of your browser any website can extract when you visit them. Which is all they need to uniquely identify you in this wast ocean of internet users. Disabling cookies or using proxy IPs becomes essentially meaningless since your browser alone has very unique fingerprints.
A nice article on Browser fingerprint uniqness by EFF : https://panopticlick.eff.org/browser-uniqueness.pdf
You can get your browser tested for uniqueness here: https://panopticlick.eff.org/
My browser has "at least 22.3 bits of identifying information." which pretty much makes it unique in the world. Goodbye to privacy :(