It's far too early to bejudging any of these men in terms of history. Perhaps Nixon, it being nearly 40 years ago since he left office, but that's still a little early. It's my feeling that a president would have to be out of office for at least fifty years before we could get a true perspective on his administration. Much less than that and you still have the problem of partisanship.

That doesn't mean people can't have their opinions. Just that there's little justification for claiming an accurate ranking, especially for Bush and Obama, and even for Clinton. History and historians must take a longer view of such things.