Preferably lesser known but game-changing apps that are able to be bought one-time and put all others to shame.
To help clarify your thinking, which apps have produced such an outrageous level of value (regardless of one-time cost) to the extent you believe it should be #1 in its category, not necessarily #1 app ever.
We’ll do a seperate thread for Mac, Windows, Linux, Android, etc but let’s stick to iOS for this one. Thanks Lemmings!
The one I wrote myself to automate tasks at work. It has saved me hundreds of hours of tedium and makes my job so much easier. It only cost me a few weeks of learning (I am not a developer, just a tinkerer) to get it done. It lives happily on my phone and iPad and I use it every day.
You wanna tell us more? Kinda hard to act on this :/
Edit: I might do one on Shortcuts although that might be trickier given the lack of anonymity in “sharing” them since its iCloud and tied to your Apple account :/
Oops, I’m sorry - I should have mentioned that it’s not on the App Store. It is chock full of company proprietary documents, photos and sales formulae. I wrote it just for myself.