It's not just an opinion that Firefox regularly phones home. It also uses privacy-hostile services such as Google Search by default. It has an economic incentive to do that since Google, etc. are the ones who fund them.
As the website says your best options are GNU IceCat or Ungoogled Chromium with uMatrix and HTTPS Everywhere.
As the website says your best options are GNU IceCat or Ungoogled Chromium with uMatrix and HTTPS Everywhere.