Having had a deal of experience here i think that it really depends what you need to manage on a given box. Find your most common use case and ask a more specific question in terms of: whats the best tool for managing that. Things like IIS can be tricky (on older windows builds at least) and finding modules for CM tools to manage things like IIS settings and app pools can be hit and miss - especially when it comes to advanced settings (worker thready recycling springs to mind)
However Puppet has forge modules for more basic IIS settings which largely worked for me - and i really like the declarative format here - especially if you are managing large numbers of IIS servers
Also one of the major issues with Windows and configuration management is the lack of a proper package management solution - what actually comes in really handy here is something called Chocolatey (see http://chocolatey.org/) there is a plugin to use this as a provider in puppet - making the whole management process particularly easy. However i imagine that this can be integrated with other CM tools aswell - but does a great deal to help with installing software automatically in a windows environment
Though it is worth stating that whatever you end up using you will have to spend a while figuring out some odd bugs - windows and scripting/automation is not the best.
