Whenever you begin to think of doing an LLM, the first question that comes to mind is "where?"
Deciding where to attend the LLM is a very important question that can affect the final outcome of your LLM. So you start doing research to see which law school is best. Google.com. Search. "Best law schools in USA" and the first result is the Best Law School Rankings from US News.
This is probably the most respected ranking out there but, is this the best raking? Deciding which ranking is best is almost impossible. There are way too many variables out there: location, specialization that you want, what do you want to do best, etc.
It is said that if you want to become a studious of the law you try to attend Yale Law School. If you want to become a corporate lawyer the best one is Harvard Law. If you want to do capital markets, you would choose Columbia. Private equity? Go to Stanford.
Why? They have the best reputation, tradition and they are in the key cities for it to happen. Does this mean that these are the only options? Absolutely not.
First, bear in mind that the US News ranking is meant for J.D., this is, American students going for their law degree. So it is more general than anything; second, ask around. I am sure you have connections to someone that did this or that LLM. First hand knowledge is always good; and third, there are specific LLM ranking that can help. This web is useful. But there are others.
So do your job, ask around, think it through and decide. Applications are expensive and you would want to narrow your short-list to 3-4 and then tailor your motivation letters to each one of them.
Let me know if you have any questions in which I can help!