<p>NU is superb in the areas in which you are interested.
You would also have research opportunities aplenty.
Almost all courses are taught by profs, but sometimes there is a weekly review section led by a TA.
Both of these schools are absolutely superb, among the best in the U.S. You cannot go wrong, so my advice is to pick the type of school, in terms of size, atmosphere and location, which appeals more to you. They are completely different in those respects.</p>