Trust is a tough problem when you go deep enough down the IT security rabbit hole. I personally trust software more when it has a public github you can look at and see exactly whats being worked on or added to code base. Generally forks of browsers like Firefox or Chromium like to stay up to date and so are updated within a few days of the new browser release if not shorter. There are some older browsers like palemoon that do their own thing independent of current firefox releases but in general most forks you would want to use are regularly updated and fast.

I like Librewolf. Their website is pretty clear about the differences in goals. Firefox by default has a lot of its security features disabled so to not break website compatability. Not just in regular settings either but the real nitty gritty stuff in the about:config section. Firefox also has sponsorship stuff activated by default so mozilla makes some money. Librewolf has more of these security features enabled and rips the sponsorship stuff out. It also comes preinstalled with UBO.

You can go even further beyond with advanced security profiles like arkenfox's user.js. Remember though theres a trade off you are making between security and convinence. The more locked down your browser the more things are gonna break or more personal inconvinence youll have to deal with. Cookies that last multiple sessions suck for security but damn logging in over and over and over gets annoying. So I've been there, i've done that. The pain in the ass that comes from a super locked down browser wasn't worth it for my threat model.