[j1elo]

Meld [0] (written with GTK so available on Windows, Linux, and possibly Mac but I don't know about that last one) is another tool in the first category.

WinDirStat [1] (Windows) for the second. It is also available in the super-useful PortableApps format [2], which is always nice.

[0]: https://meldmerge.org/

[1]: https://windirstat.net/

[2]: https://portableapps.com/apps

[Semaphor]

WinDirStat is extremely slow compared to WizTree, give WizTree a try :)

[fragmede]

`ncdu` is my preferred Linux ncurses equivalent to windirstat