If you like Debian and like to help make it better, and also want to use testing please review this guide where I try to cover many common things and improve your experience:
Besides Firefox ESR, it came bundled with "Konqueror". Don't know if it depends on your installation's configuration, though. I selected to install "non-free" software, if it helps.
So for me it didn't complain when I uninstalled Firefox ESR, it just set Konqueror as the default web browser