Choosing Between the SAT or ACT

Hello, I am an upcoming senior with the goal of attending Yale in the Fall of 2018; however, my SAT and ACT scores seem to be my biggest hindrance. I need help deciding which exam is better for me. I have taken both once, with my most recent SAT being a 1280 composite (680 RW, 600 M) and 27 ACT (35 Eng, 27 Math, 24 Rdg, and 23 Sci). I know that the main reason that my scores are not up to par is because I did not spend nearly as much time on the exams as I should have. Could anyone on the PrepScholar team please follow up with what I should do? Thank you in advance!