I'm not sure about the scope and details of Germany's attempt to switch to Linux, but for the average user, any of the popular distros would likely serve them well. I think there's a huge difference between a user installing Linux on a general purpose PC vs. trying to incorporate it into an entire country's worth of devices.

I've heard horror stories of people spending loads of time tinkering with their OS to fix obscure issues, but generally, these distros are often as easy-to-use (if not more so) than Windows these days. I think the main issues people have stem from software built specifically for Windows that won't work on Linux, which hardly seems the fault of Linux imo.