I'm playing the Meditazione sopra "Herzliebster Jesu" by Italian composer Carlotta Ferrari on the 1911 Bernhard organ: in this video from March 2021, there are two versions. First version: Prinzipal 8' as the solo stop. Second version: Flûte harmonique 8' as the solo stop.

Still don't know which one I like better, that's why you get both.