What science course is better for a computer science major?

If you want to attend a top tier school I would recommend taking chem since it's AP. It's more rigorous which selective schools love to see. For calc I would ask your math teacher if they think you could skip pre calc and do well. Chances are if you did well in your previous math classes they might let you skip it if it's not required to take pre calc. You only have four years of high school, already deciding to take an extra year than the required demonstrates you are taking advantage of your time. If you can take pre calc during the summer without inconveniencing yourself I would try. Aside from admissions it could really help prepare you to have already taken them while in high school. My sister is an engineering student and only taking pre calc before was a big help because she had that foundation and was still practicing her math skills continuously rather than having a year gap. The only other thing I would say to consider is if it takes to much time I would drop it to focus on EC's. But if your EC's are already strong take it.

I think there is a point with APs made below, and that AP Chem has lots of applications with Comp Sci in Computational Chemistry fields and Chemical Engineering. However, computer scientists who do programming generally need to be good at problem solving, which I think Physics is a great class for. If you can take an AP Physics Test on top of your honors class, that could work too. In my AP Physics class that I am in right now, I'm self-studying for AP Physics C Mechanics with Calculus (its not that much different than honors Physics or Physics I, just about 50% more content). Note, top institutions do not take scores for Physics I for credit, only Physics C really which I learned the hard way, lol. Quantum mechanics is huge in computer science and could be a field you prefer.

That being said, AP Chemistry was a lot easier for me than Physics, although I feel like the equations and memorization in AP Physics is probably easier. Thus, AP Physics will push you harder and to be a better thinker, which I think could help you in the long-run.