If IB is your goal - CBS seems a no-brainer.
I am a first-year at CBS and while I did not recruit for IB, the IB Club here did an incredible job of supporting people who wanted to recruit for IB.
Plus, you have the added bonus of easy access to not just big-name IBs but also some smaller ones. This is important, especially when the economy sours.
People from Chicago/Boston etc., have to make the trip to NY sometimes for networking...being in NYC gives you an edge/ saves you time.
Additionally, NYC is a great place to be for 2 years. Finally, you have a higher scholarship from CBS, so that makes your financial burden that much lesser.
Having said all of this, do what you feel best. You must have done your own research and talked to current students/ alums from both schools. If you felt better talking to one over the other - you might want take that into account when making a decision.
Booth or CBS are both great schools ofcourse. So you cant go too wrong with either.
Congrats on the admits and wish you the very best with whatever decision you make.

Edit:
Adding a few more points:
1. CBS has Grade non-disclosure as well so everyone is very relaxed about academics (not competitive but collaborative).
2. If you apply for Columbia Housing your rent will be anywhere between 1300 and 1800 per month.