I recommend Mull. It is security/privacy hardened Firefox and built by using Fennec as a base. Always use Fennec over Firefox because it removes telemetry, proprietary code, and strongly protects against browser fingerprinting. Comes with support for most (if not all) desktop Firefox extensions. I highly recommend using uBlock Origin, ask anyone and they’ll tell you it is the best content blocker available.

Another good browser is Cromite. It is security hardened Chromium with built-in ad/content blocking, decent fingerprinting protection, and strong site isolation. It doesn’t have support for extensions because upstream Chromium on Android doesn’t either and it is hugely complex to port.