I am an IB Diploma program candidate (currently a junior) and I can definitely say that, even if not for admissions purposes, IB is a wonderful program that will prepare you for anywhere you go in life. I may be biased here, but I think IB is a fantastic program and requires a little more hard work that AP.
You have to consider the fact that, unlike AP, where you can pick and chose what courses you want, IB requires you to take almost a full course of IB classes. (At least 3 HL and 3 SL). I am taking HL Biology, English, and History, and SL Physics, Spanish, and Math, as well as TOK. It is a lot of work!
There is more than just demanding classwork and hours of studying, too. There is also a required amount of CAS hours that need to be done (essentially community service, CAS stands for Creativity, Action, and Service), a self-designs and run CAS project, Theory of Knowledge classes, a 4,000 word “extended essay”, and lots and lots and lots of testing. Unlike AP, which has one test per class, IB is made of several tests (IA’s, EA’s, IOP’s, IO’s, WA’s... lots of acronyms to learn!)
A lot of people don’t think that IB will prepare you for a STEM degree, but it absolutely will! I plan to major in engineering myself. The math and sciences classes are wonderful and challenging. There is a more “worldly” and “cultural” emphasis, but this only adds to the experience. The IB emphasis on culture and world views makes learning more valuable and makes you think for yourself and at a higher level.
Understand that being in IB is far more demanding that AP, at least to me (at my school, we call IB classes “AP classes on steroids” haha) but the rewards and benefits are countless. You will have to work hard, manage your time around everything else your doing (ECs, Sports, work, etc...) and put in a lot of work, and a lot of long, sleepless night of studying and cramming, but I know that whoever I go to college, and wherever I go in life, I will be prepared for anything. IB teaches time management, group work, leadership, study skills, stress management, and hard work ethic. There is a lot of benefits that you don’t really get in AP.
If you are up for the challenge, go for IB! It looks great to admissions offices, whether its a service academy or a civilian college, because they know you are putting in a lot of work and dedication to your academics. Some civilian colleges even give scholarships to IB students, and if you test well enough, will let you start college as a sophomore. It also makes you stand out among to huge group of AP students, as IB is less common. In the end, it is a great program and shows that you are a strongly dedicated student and are going above and beyond for academic scholarship. I wish you the best!