As KJ has summarised, the German law is a bit vague, but you should have "appropriate" tyres. So, if you are caught blocking the road on an icy slope with spinning summer tyres, that will be 80 Euros or whatever, thank you very much. Worse though, as expected, it is a way for insurance companies not to pay out if you have an "off" in winter.
I've found that most good winter tyres are fine. The FIAT is actually on a pair of Dunlops and a pair of Contis (after a puncture that could not be repaired and the Contis were no longer available, nearest equivalent was the Dunlop). I should probably get a new set (due to age) but I'm not sure that I want to keep the car much longer, but that is another story.
The Subaru's on new Michelins - very refined for a winter tyre. As with other tyres, the major makes produce good enough products and it is hard to go wrong as long as they are the latest designs. The Jaguar is on Pirelli Snowsports and they are noisy! But they are really old so should go in the skip. Then again, they are only for emergencies and avoiding the sumer tyres going out of shape as the Jaguar winters indoors.
The ADAC test is not a bad place to start for a shortlist. Any of the recommended tyres will be absolutely fine, so I would get the cheapest, or the quietest, or the one with the best life, or whichever secondary characteristic is most important to you.
Top 3 this year were:
Michelin Alpin A4
Continental ContiWinterContact TS830P
Dunlop SP Winter Sport 3D
http://www.adac.de/infotestrat/tests/rei...rcePageId=31821