I realize you state you're settled on a desktop but . . .
I always had a desktop at home but quickly figured out a desktop probably would not be ideal for a full-timer's lifestyle. So I decided to get a laptop with a nice big screen for my 67 year old eyes. I settled on a 17 inch non-touchscreen Dell with Win10 and bought it using Amazon. I also added a wireless mouse and a wireless full size keyboard. Works great and takes up way less room then a desktop.
I was a little worried about Win10 because of all the stories out there but I like it a lot. It's optimized for my non-touchscreen machine. I think you may be happier with Win10 as a pre-installed operating system as opposed to an upgrade on an existing machine - just my guess.
I had also decided to add a standalone larger screen if the 17 inch screen proved to be too small but I don't need to do that.
I also have a large external hard drive for pictures, etc. (they are relatively cheap).