I've used both technologies in C# for some time now and thus far have not been able to figure out which is better (in terms of ease of use). It seems to me that because there is support for Windows 95 in WMI, it's an older technology than ADSI (which I assume was invented along with Active Directory). However, despite the hint that ADSI is "for AD", I've used it for several non-AD things, such as managing IIS and local users.
So, for those sort of tasks (managing IIS and local users), which is more practical? WMI or ADSI? Consider also that I'm using C# to implement these technologies, not vbscript. However, this may equally apply to vbscript.