if you are looking for a hardcore, objective factual list, forget about it. a lot of economics is like art, you will find
now about rankings, so the least disputable rankings are the ones with the fewest schools...top 6 = harvard, mit, chicago, princeton, yale, stanford. Even here penn, NYU, northwestern, have claims.
there are basically 15-20 schools in the top 10 and 30-40 schools in the top 20.
coming from a person who uses rankings all the time, think about rankings like a crutch for those who don't have much vision about what the profession is really about