The Move is basically hi-def Wii. The Wii already has a huge library of good games that work with the system (and a whole pile full of shite ones), whereas the Move has only a few at opening. From the demos I've seen, the lag is the same in the Move as in the Wii, and the cost is about the same.
I think Natal is the better of the two, as it removes the need for controllers altogether.