I generally use F-Droid for two kinds of app installations: those made available through third-party F-Droid repositories and reproducibly built apps (making migration away from F-Droid simple if needed). Beyond that, F-Droid is also a great starting place for app discovery because of its long history and mindshare among open source Android app developers. I don’t think that means apps in F-Droid are safe, but I don’t believe that would be the case for any app store without curation anyway. In fact, I am curious whether there have been any community-driven curation projects to overlay all the app stores.
Personally I find Obtanium/Github quite difficult to use. I update apps via Tor and often have connections timeout or refused by Github. Although there is nothing I can really do about it, I am not so pleased with the large majority of open source projects being developed and hosted on Github in first place.
Accrescent is in alpha, so while I can potentially understand some of the benefits behind its design it will currently always come with caveats. For example, right now Accrescent is re-writing some of the logic for the app to resolve critical discovered bugs. As a result new versions of apps uploaded to Accrescent do not show in the app.
So far I have avoided apps that are only available on F-Droid or Google Play (like Antenna Pod). I completely understand the decision the developers have made, but I think it’s also fair for me to use my time on apps that put more effort into being available outside those two.