I've managed to accumulate a small selection of old pens - mostly ringtops - with semiflex to superflex nibs, and there are small and almost indescribable differences in the quality of the lines they make. I have Watermans, Moores, Wahl-Eversharps and a couple of Mabie Todd Swans, and the most beautiful line is produced by a little gold-clad Swan. There's some combination of metallurgy and craft (perhaps witchcraft) that makes some pens more "artistic" than others.
What's your experience? What nib, in your humble, is the most Artistic?