Well, maybe the default configuration doesn't. However, it should be possible (from what you wrote, I don't do Gtk) to configure the dialog to filter on the average width.

That, in combination with the spacing type being either m(onospace) or c(character cell), should give you most of what you want (at least if the dialog itself remembers both last choice and filter). If there is a way for XEmacs to get its hands on the filter setting, then XEmacs could use that to make good choices of appropriate defaults for logically related faces. Am I missing something? But this is in theory: in practice some X servers will do horrible things if you try to do that (autoscaling, in particular).