Obtainium has been my go to for open source for many years now. You don't want to be relying on fdroid when you can add direct from source code releases. Up front config required but can backup and restore easily after that.

Zapstore coming along nicely but not as flexible and doesn't have all the apps you want yet.

Aurora store for the handful of proprietary apps you might still need or are in the process of transitioning out of.