First of all, I'm a Linux User and know that df and tons of other CLI tools exist. I'm only looking for a GUI tool, this makes this question relevant, so please don't mention CLI tools.
In the GUI arena, we do have tons and tons of disk analyzer tools. They don't work for me, what I need is a simple OVERVIEW over all media that is attached to my system and be able to use a GUI, basically what df does, but with a visual usage bar. Windows does this well, as the pic below shows and I raked my brain and the Internet to find such a tool and so far, zero.
The disk analyzer (where is your space used) are overkill and do not allow to show the total for several disks. Also, I don't want a tool to bog down the system, when a simple check for disk space totals is enough.