If you're looking for a distribution for an aging machine and you want to go with something other than a Ubuntu-based distribution, walk through the Arch with Omega.
The "Linux vs. Windows" argument is just ridiculous.
You can learn a lot about Linux by just trying different distros, but using Proxmox will force you to learn a lot of in-depth ...
I've used Windows for decades, but I tried Linux to see if it's truly 'easy' now - and one thing surprised me ...