Cornell or Dartmouth?

SAT: 1420/1600
SAT: 31
GPA: 3.5

Volunteer work: Throughout high school I’ve volunteered at my local hospital. I’ve also volunteered at my local church for the kids summer bible camp.
Extracurriculars: I had to stay home a lot to help my mom raise my 8 younger siblings. I’ve also taken chorus classes after school at my high school.

Do I have a better chance at Cornell or Dartmouth? Do I even have a good chance at either? Which one should I apply using early decision?

Cornell is significantly easier to get into.
But with those numbers the chance at either is very very low, nearing zero.

Your test scores are in range but not stellar. Your GPA is low. Your relative lack of ECs needs to be balanced by your other obligations. No idea how that might play out. There better be something else in the application.