Wow that's cool. Thanks for posting that.
I can vouch for the Black Forest High Road that is a great route, lots of sweeping curves and fantastic scenery - and the Grossglockner Alpine pass is even better, a mountain pass with a load of varying switchbacks. In my opinion, both are better than the Stelvio pass (but that might be because I had a lot of traffic there). For context I've just come back from a road trip in Europe taking in both of those routes.
Everyone in the UK knows Snake Pass but these days unfortunately its kind of ruined by numerous speed cameras due to the number of biker deaths on it over the years.
Edit: there was an even better road that I found by accident coming down from the Grossglockner pass on the way to Venice. Just coming into Italy and it looked like a pile of blue spaghetti at times on the SatNav. I think it was the road from San Candido to Santa Croce. A mix of mountain switchbacks, long sweeping curves and quite a few tunnels. Fantastic scenery, little traffic but some overtaking points if needed too.
