I keep about 55GB of system ISOs on my server, as an archive. 28GB out of that are w*nodes ISOs. Most of these are the ISOs I regularly use or are hard to find (like win11 old enough to make a local account, Orange Pi Zero 3 proprietary Linux image, etc)
I also seed a few of armbian and proxmox images, so that would be another 50GB.
And I have a 128GB Ventoy USB thumbdrive which is almost half full with ISOs, most of which are Linux