I think the indoor plumbing is first and the toilet tissue comes a close second. Close your eyes. Though I too am partial to sporks. It's a bogus question guys. Think about it.
Nobody really invents anything totally unique.
Everything is build upon things somebody else invented. Take the flushing toilet for example. The Roman aquaduct system was a precurser to that even. I would say the greatest achievement of the millenium is that we haven't totally ruined the world yet. Yes electricity is part of the best technological innovation of the millenium, but it is a discovery.