Before entering my account password, there is a small gear whereby I can select amongst 6 choices:
-System X11 Default
-GNOME
-GNOME Classic
-GNOME on Xorg
-Kodi
-Kodi
So far I assumed that any one of the 3 GNOME choices would be good. Anyone has a strong view on which choice above works best with PureOS? Any pros and cons for each that you could observe?
GNOME means Gnome on Wayland. This is not spelled out, signifying it to be the “normal”, default mode.
GNOME on Xorg looks exactly the same. Unless you want to access your desktop via remote control tools (like vnc, TeamViewer or thelikes) you should have little reason to use this legacy mode. When Ubuntu switched back to Xorg by default on Ubuntu 18.04, the unavailability of a remote control API on Wayland was the main reason for that. Still, there’s no doubt the future will be on Wayland. Purism plans to have only Wayland on the Librem 5, and might also remove Xorg from PureOS sooner than others might.
GNOME Classic is also Gnome 3, but it’s supposed to look more like Gnome 2. So it’s just about your preference 