If I am being completely honest, there are very few. Convenience is consistently the #1 trade-off when I make privacy-based decisions about which applications and services to use.

An exception I can think of are ad and tracker blockers like uBlock Origin, iodé, etc - I cannot imagine life without them Any time I borrow the phone or computer of someone who doesn't have an equivalent of these installed I am just blown away by how many ads they are confronted with while performing even the simplest tasks. And not just harmless ones, but ads that directly waste their time. I genuinely don't understand how people can live like that unless they just don't know there is an alternative.

I guess another one I can think of is the Aurora Store. The UI is so much cleaner than the Google Play Store's, important settings and features aren't hidden and it has some additional features like Exodus Report that I think are genuinely useful. It's so superior as an application that I actually prefer using it even on devices where the Play Store is installed and working.