Like others have said there is no binary answer, its all dependent on what you have to achieve
Safari is best if you want extensions and require the best integration with iOS but its main drawback for me has been when you limit adult content in the screentime settings you also lose access to private browsing mode.
Firefox Focus is wonderful from a minimalism perspective as it forces you to do things in one browser session and for security I find it useful for when you have to access links you cant trust but you can achieve these in other ways
Brave is good option if you want to sync across different platforms and just want a good OOB privacy experience, but if you simply just want content-blocking there is always adguard, you can block scripts on a per-site basis on Brave which I love but it feels incomplete in my opinion due to things just being straight up broken under Lockdown Mode.
Im really torn that there is no way to configure it in 3rd party browsers 
There is always the option of using multiple browsers which some would argue is better approach anyway