Should I take an AP class my senior year or take the equivalent class (Chemistry) at my local community college over the summer? Which would look better to a college admissions office?
My advice is to take AP Chemistry. Leave your summer open so that you can potentially use it study for standardized tests that you plan on retaking senior fall. Your test scores will influence your admissions chances much more drastically than your decision to take a college class versus an AP class. The AP class could actually look better on your transcript if the colleges where you're applying are not familiar with the reputation of your local community college (they won't necessarily know what an "A" really means in that class).
If you want more information about the pros and cons of AP classes versus community college classes, I'd recommend reading this article. One class will not make a huge impact on college admissions chances, so don't stress too much about it!