I'm parking the first vote with Karlsruhe for now, even though Moscow appears to have a better/larger collection. It doesn't seem as nicely presented as Karlsruhe, and from what I've heard a lot of the goodies are off-show unless you ask or are invited to see them. From a general visitors point of view that's not a great idea.
Marwell wasn't even in the running on this one, I've only visited once (and that was only a couple of years ago!) but the bird collection was pretty lousy, bar the secretary birds obviously. Marwell really drew the short straw here, ungulates and carnivores may have gave it a chance but definitely not with birds!
Anyone want to convince me to change to Moscow ten I'm willing to be persuaded.
And also, Karlsruhe has a very nice website. Never visited it before but it's very well set out even via translate.![]()