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 built-in document scanning shortcut. It’s a Files feature. If you go to Shortcuts and search files you’ll see it. It can be put on the homepage or dock for easy access.
Just wanted to give a shout-out to QuickScan as its better than Abbyy FineReader/Scanner, private, and technically free although I support it by tipping