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.
Well I basically never use SMS, so I have no idea if they work for me or not.
At the moment I’m using it to connect my two laptops and phone, mostly for notifications, file and clipboard sharing and remote trackpad.