COSMOS vs. Volunteering?

Should I do cosmos, a month long program or should I spend that time doing volunteer work?

To begin, I want to do COSMOS to learn something and not to use for my application. However, if I do it, it won’t let me volunteer at a local hospital or teach kids robotics, both of which I think are absolutely amazing and very fun, and will actually benefit my college application (I am not putting a summer program)

COSMOS might also interrupt with my summer homework with 6 AP classes, because I will want to have fun with people because I want to be very social.

Should I do COSMOS, or find another shorter program to do that is selective and very good?

Thanks!