What is perceived to be better for admissions purposes.
1500 SAT - one sitting - 770 M, 730 E
34 ACT - superscore two seatings - 35M, 35E, 34W, 30 Science
At DD’s top school, the 34 ACT superscore places her right at the 75th percentile. While the SAT 1500 places her right below the 75th percentile, but I think the one sitting on the SAT might look better.