I think it depends rn. Vanadium is a very good browser. It is not yet the best singular solution for all use cases. For example, I do not believe GOS would recommend Vanadium to replace Tor or Mulvad browsers in cases where privacy through anonymity is needed
Vanadium is secure as hell. I use it as my daily driver, applications with a security implication, and situations where I have already been directly de-anonymized.
I do not think Vanadium has much anti fingerprinting built in yet, and the user base isnt yet large enough to obfuscate it's signature end masse. But if some level of privacy is needed to a greater extent & security is a lesser concern for a particular case, Brave may be a strong middle ground
Brave & other browsers will add massive attack surface to GOS. Vanadium is installed by default, and it known to be trusted. That's probably the strongest case for keeping the default browser for all use cases
I would consider Vanadium to be stronger and more secure than installing third-party apps for services that support browser. At a bare minimum, it's less attack surface. You can also be sure that Vanadium itself isn't collecting telemetry, as many apps do
NoTimeDaddy Braves Add Block is superior to Vanadium
Browser-level adblock on a mobile device is an odd requirement. I'd recommend looking into something closer to the network level, like rethinkDNS or NextDNS