I'm in almost exactly the same boat, so I'll be interested to see what the folks on the forum say about this.
PoetsandQuants.com has an interesting analysis on NYU vs. Columbia, which is definitely worth reading, but I don't know that it's put me any closer to making a decision between the two schools.
Here's what I've been thinking about so far:
Recruiting: For the most part, it seems like most of the same major marketing recruiters come to both schools.
Marketing Department: Columbia is ranked #6 in US News (while NYU doesn't make the top 10), but I wouldn't put much weight in this, since they get many of the same companies to recruit on campus. Based upon a 2010 Princeton Review
book, 8% of Columbia grads go into marketing, while 20% of NYU grads go into marketing. Looking at the overall class sizes, Columbia probably has around 50 people going into marketing per class year, while NYU probably has around 80.
Rankings/Prestige: They're neck and neck in the US News rankings, though some people might say that Columbia has a better overall reputation because of its longer history as a top business school.
Size: Columbia's total Full-Time MBA has about 1,300 students (which puts it on the higher end), while NYU has around 900 (in the "medium range"). This could translate into smaller class sizes, or make it easier to get one-on-one time with teachers. It should also have an impact upon the overall "feel" of the school.
Campus / Location: The immediate area around NYU is definitely a bit more fun and interesting, though it would be more expensive to rent an apartment near NYU than to rent one near Columbia. Regarding the actual business school facilities, NYU definitely wins. Columbia is building a new campus, but that won't be finished until after we all graduate.
Overall: Definitely a tough decision, but I think that I'm leaning towards NYU as of right now. I'm going to try to pay another visit to each school before I have to make my final decision.