Question: Do colleges care more that you took an AP test or that you scored well on it? Or do they just care that you took an AP class?
If you're looking to apply to top colleges (Ivy League and other so-called "elites"), you'll want to not only take as many AP courses as possible and do well in them (As or Bs) but also take the tests and do well (5s or 4s).
If you take an AP course, be sure to take the test too. Some students mistakenly think that just taking the course will attract positive attention to their records. To the contrary, if a student takes an AP and then does not take the AP test, it will attract negative attention to his or her record because the college will have no way of knowing how well the student mastered the course material.
Also, if you are looking to earn AP credit at a college, you'll need to confirm your mastery of the course material by doing well in the AP exam. At some colleges, a good list of AP-course successes might earn you a full semester's (or more) advanced credit, thus allowing you to either graduate sooner (saving time and money) or allowing you to exempt some distribution requirements (required courses within your major) and then be able to take additional electives or advanced-level courses in your major.