For Windows, WizTree because it’s extremely fast. For Linux, I like ncdu

Space sniffer. Visual size representation, and easy to jump into directories.

Just the standard Disk Usage Analyzer that ships with my distro. The visualisations are nice and the nesting of dirs is very clear.

If I’ve understood the question as you intended it, on windows I use treesize, on Linux I use NCDU

K4DirStat

I use the configuration app on Windows 10

Filelight because I’m lazy to search alternatives & it already works as I want, plus Qt theme

Also interested.