The cache with most favourites i found is located in Hamburg.
|GC18182||Voss-Margarine|| Hamburg||4684 (82%)|
It is a small multi-cache, where you first have to count some signs and then you have to find a unique tool (self-made by the owner). With that tool you have to reach for the cache and to get it from its hiding place. Very cool built container that fits perfectly in its surroundings. You have almost no chance to do all this without muggles around.
I believe it is the cache with the most favourites in Hamburg. And the owner has built some more of very cool caches.