Uber? What do you use for rides?

Xplore file browser

It's trivial to replace the independent pieces of xplore, but it has so many features in one app that I just can't let it go. It's got dual pane file browsing, disk usage chart, smb, ftp, and many other cloud storage connections. It also handles many types of compression.

It's become my main offline music player as well, because it has the simple ability to shuffle a folder of music, which is all I really need.

It can also view installed apps, export them to apk, and view and modify appdata (as non root!).

Sailforms Android app!

https://groups.google.com/g/sailforms-users

Use like 12 years for keeping track of lots of personal stuff. It's a generic database / table / forms app that's very powerfull. Buttons, queries, reports, calculated fields etc.

But: the app developer stopped despite a rather enthusiastic community. Now it isn't even on the Play Store anymore and I guess everybody must have an exit strategy.

An equivalent to iOS Shortcuts for Android and Linux.

I would really want to have a really good open source SFTP (SSH File Transfer Protocol) app, with good secure key management and excellent transfer performance. So far, I haven't found any such app.

Readably

No RSS reader is quite like it.

Synfonium

Best music player out there.

Why is there not an app that tells you which grocery stores have the best prices? I should be able to give it a list and it'll tell me where to buy each item.

Visual voicemail

https://play.google.com/store/apps/details?id=com.chimbori.hermitcrab

I don't have any suggestions. I can't think of any proprietary app good enough that I'd give up control of my computing for. However, consider objective requirements rather than subjective terms like good. What do you use the proprietary app for, why are existing free alternatives not sufficient, and can a free app be made that satisfies those requirements?