I'd rather not get into yet another "which ranking is more accurate" debate. But for the sake of students who are less aware of these issues, I will try to clarify things.
1. There's a bunch of rankings, US News, Shanghai, US National Research Council, QS. Of all of these, I would probably say that QS is one of the least useful. Why do I say that? I get SPAMMED on multiple email addresses to respond to a survey on QS university rankings. I don't respond, and they just send more mail. This is NOT the behavior of a reputable organization trying to gather a legitimate view of universities and their research quality.