Mull is fine for most people and I wouldn't really consider it an urgent deal to move over.

Firefox browsers on Desktop are much better than on Android. Mullvad, Brave and Tor are the best browsers on PrivacyTests with about the same results on each: https://privacytests.org/

Chromium-based browsers have some very good exploit protections and stronger process and site isolation but Firefox is improving well. Most of these exploit protections only really mean a lot on Windows though due to Windows-specific features.