when i start it, Dropbox acts as a real-time backup of the save game files on the main computer too… and i also have a habit of making weekly 7zip snapshot archives of the WoW save data - those will get synced over to the laptop too… so messing around with usb drives would be an inconvenience. (have some usb drives too… but i don’t use them much these days except for installing win10 from them)

Onedrive: haven’t tried it. Back in 2014 i discovered that Dropbox was behaving much better than Google Drive at preserving file name integrity and i stuck with it… even if it has that annoying registry behaviour.