The section "Securefox" should probably be renamed "Privatefox", but labels are misleading. It's best to read the project files to understand the balance taken with security, privacy, and functionality. Let's make it simple:

Want a mix of speed and privacy, while retaining functionality? Use Betterfox user.js.

Want more privacy and security at the expense of site functionality? Use Arkenfox user.js.

Want Tor prefs but without using its nodes/relays? Use Mullvad Browser.

Want anonymity? Use Tor Browser.