I don't pick a browser for the Firefox or Chromium engine (unless a site needs it), I pick a browser based on the UI and configuration management. So I use Qutebrowser that is keyboard based and a declarative configuration. It happens to use QtWebEngine but that is not why I picked that browser.
Since I don't use Firefox... I don't really recommend it to anyone. Firefox's early success was driven by educated user's telling other people to drop IE for the better product. It also means a lot fewer developer's are using the Firefox engine when developing websites... especially the developer's that would put in the effort to submit bug reports & patches.
(At least last I checked, recreating a Qutebrowser like experience in Firefox was at best just really annoying and would still lack features).