The Washington Post speculates on Greenspan's successor, likely to be chosen after the election. A Bush victory is linked to Harvard's Martin Feldstein or Columbia's Glenn Hubbard. Robert Rubin is said to have "right of first refusal" should Kerry win, with Harvard President Larry Summers next in line.
Hubbard, and Summers both have close connections to Feldstein, and Rubin's work in the Clinton adminstration was widely hailed, appropriately so in my opinion. That they understand the key policy issues is not in question. Of these, I'd choose the man with the ability to, first, maintain the Fed's independence in the face of political pressure, and second, to forge consensus on the Board. Those qualities are mighty difficult to discern from this vantage point.