AIX

My favorite X11 Server for a windows "client" is Xming.

May not be as fast as VNC, but it works easily over a X11forwarding opening.

I have to think quite a bit.... ah yes - XDMCP which uses port 6000 - is another way (old-fashioned?) to connect to one of several CDE displays.

Pros/Cons

vnc has had bad press (maybe fixed a long time ago) re: screen sniffing, clear text communication, etc.. XDMCP can have similiar problems. Hence, due to my frequent need for encrypted communications I continue to use Xming and X11 forwarding in an ssh session.

VNC is remote control software, so on a PC it could be a security vulnerability allowing a hacker to take over your desktop. As such, it has made its way onto some lists of forbidden files.

Xming is a simpler, more straightforward X Server to run on Windows. The transport is X11 not VNC, so some apps may suffer from the longer X11 latency.

Both apps are subject to the usual challenges of making X fonts available local to the X Server to support target apps.