For me, it was perhaps simple-scan, a very simple and efficient GUI to scan documents. I used it with my Brother printer / scanner and it works like a charm. Especially since I do not scan stuff often, so a program with more complex UI would have the effect that I forget how to use it until the next time.
It’s so good that it absolutely killed my will to maintain a project I had that does something like this once I discovered it. They even support Windows too.
Been there, doing that, cf https://git.benetou.fr/utopiah/offline-octopus