Is IB or AP "better" for college?

The simple answer to this question is that AP is probably a better bet if your primary focus is to earn college credit. While the IB will earn a great deal of college credits, the program entails additional requirements and presents a very specific philosophy of learning. A student should consider IB because they are excited by the IB philosophy, not to earn college credits. That being said, our inaugural IB graduates of 2012 did exceptionally well in the college admissions process. It appears that on average, IB students were able to get into more competive colleges than their peers when controlled for class rank. 
If you are primarily interested in gaining college credits, the AP program is probably your best option. There are several reasons for this. First, since AP is the more established program, more colleges recognize more AP exams. Since IB is a "newer" program, it is sometimes misunderstood by university admissions offices. Some colleges will give credit for "HL" classes but not "SL" classes. This is because they are under the false impression that "SL" classes are somehow less difficult. However, there are several trends that are beginning to counter this. In general, colleges are giving less course credit for any high school work. At the same time, more colleges are recognizing the rigor and intensity of the IB Program. 
While AP focuses on college credit, IB focuses on college admission and success. This is certainly not to imply that AP students do not have college success, but the IB Programme is designed with this goal in mind. IB believes that general success in life and in college share many common elements. First, all students should be "internationally-minded." This term is meant in its largest sense. International-mindedness doesn't only deal with striving to understand the perspectives of other nations, but of other people generally. IB believes that critical thinking and international-mindedness go hand in hand. As such, IB stresses the importance of thinking critically and writing across the curriculum. This is part of the reason that a 4000 word extended essay research paper is required. Further, IB believes strongly that "learning" is not simply what happens in the classroom and that truly well-rounded students must be engaged in their communities as well. The 150 hour Creativity, Action and Service (CAS) element requires that all IB students be active and involved in their own communities as well as in the international community. Finally, the IB program emphasizes the importance of intellectualism, academic debate and critical questioning. As such, all students are required to study Theory of Knowledge (TOK) or epistemology for 100 hours. The IB Programme brags a nearly 100% college retention rate. Students who complete the IB Programme simply do not drop out of college.