I'd say Columbia University. Both are pretty good in terms of prestige, rankings and job placements. They are both similar in many respects so you really cannot go wrong with either one. It all depends on your personality and whether you fit NYU's atmosphere or Columbia's atmosphere.
Take a look at this link. Notice where Columbia & NYU falls and how close they both are to each other in rankings.
Search - Business - Best Graduate Schools - Education - US News and World Report