I would put OSX as the best I think what hold its back in the server arena is only time. In time when it establishes itself and in that time they need to make up their mind go after Solaris and IBM targets or try to hit Linux..
Part of why he put apple second was not just how it treats the network, but also about how the kernel and BSD layers are purposely casterated.
Things weren't broke and apple fixed it.
In both cases, windows was dead last.