Server 2003 was the last release supervised by Cutler, so would have my vote. It's even source-available... technically.

Cutler himself wrote code for Vista/Longhorn though. I don't know what you mean by "supervising" it. He also led the efforts for "PatchGuard" kernel protection mechanism that was introduced with Vista.

Source: I reviewed Cutler's lock-free data structure changes in Vista/Longhorn to find bugs in them, failed to find any.