As underscore noted, different programs approach scholarship in very different ways. If you go to MIT's LOG program its like getting a substantial scholarship. Kellogg is one of the more generous schools with small to medium amounts (lots alumni specify gifts for scholarships). You also have to factor in a schools endowment, there was a post with endowment totals at some point on gmatclub. I know the top 3 were HBS, Stanford, and surprisingly Kellogg came in at 3rd...though not sure how that has changed with the markets crazy over the last few years (this was after Booth's naming rights too I believe).
Just because schools give money doesn't mean people wont go there...they want to attract the top talent. So UNC is using money to try and sway some people who they realize probably got into Duke to attend. Some schools may give small amounts to sway people over peers and large amounts to snipe talent from higher ranked schools based on the individual.
Opinions on rankings for this thread are funny...how did a bunch of schools not involved in the decision come up. MIT vs Kellogg vs Booth in a discussion about kid deciding between Duke, NYU, UNC for Marketing??? really does that belong? If he got in then yes but since its not on the list focus on the topic.
Of those schools, Duke has the best rep in terms of Marketing...depending on the money it will be a wash living in NYC vs Durham is going to cost you a lot more. I know plenty of people spent their scholarship money anyways and had the same debt they otherwise would have had. If you want the northeast post graduation NYU probably will have plenty of marketing gigs available or at least willing to let your network your way into. NYC is a hub of marketing. I would skip UNC and focus on Duke vs NYU...if you havent visited I suggest you do. You will notice two very different cultures both at school and outside of school. You are going to spend two years there and both will offer you great opportunities afterwards, so look at where you belong not just the post graduation. If you get a job out of Duke, I bet you would be able to get the same or equivalent job coming out of NYU...its not like they will force you to become a banker if you got to NYU.
Kellogg Class of 2010...still active and willing to help. However, I do not do profile reviews, don't offer predictions on chances and am far to busy to review essays, so save the energy of writing me a PM seeking help for these. If I don't respond to a PM that is not one of the previously mentioned trash can destined messages, please don't take it personally I get so many messages I have a hard to responding to most. The more interesting, compelling, or humorous you message the more likely I am to respond.