May 31, 2020
The SAT I is the more commonly accepted test for elite admissions (Ivy League, etc.). Colleges in the Midwestern and Southeastern U.S. tend to prefer the ACT, but overall, the SAT is king.
If you feel that you can do better on the ACT, then go ahead and take it. Colleges make a conversion of the ACT scores to see your SAT equivalency. Why not take both and see on which one you do better, then submit the better score?