

I think your assessment of Linux Mint with XFCE is a really good first choice. Cinnamon could be worth a try though as the UI is a bit more modern looking. I’m biased towards XFCE because it looks fine and runs extremely well on old laptops. I’ve got a laptop from 2008 running it (it’s my only computer that still has a disc drive) and it’s honestly a usable machine again.
This is kind of the less powerful variant of the paperclip problem.