US News has updated its rankings of Economics PhD programs. Their rankings are based on reputation, measured using surveys. This is, I think, the best way of getting at one of the main things prospective students should consider: in general, the programs which will give you the best chances at getting a good job are the ones that people think are the best. That is why I prefer the US News rankings over studies that try to quantify the research productivity of departments.
That said, any ranking is imperfect (especially any ranking where the University of Virginia is tied with Ohio State - good grief!) and there are many issues to consider; my advice for would-be economics PhD students is here.