We've stayed at both in the last two years. It's tough to decide on which on we like better, but I think I would go with CSR. The buses are less crowded, the food court, even though a little more in price, has a much larger selection and Maya Grill has a great breakfest buffet for only about 10 bucks, larger and more modern pool (CBR pool is old and shows it). Both are large resorts, but I think CSR is more managable. CBR rooms have been recently renovated and look great and the CM's there are the best we've had at any disney resort.
Just remember, which ever one you don't stay at on this trip, you can stay at on your next.