okay, so my brother worked as an admissions consultant for a year or so after he received his bachelor’s degree. he told me, and i have heard this from other sources as well, that ivies definitely prefer the SAT. this is because it is easier to differentiate between all of the high-achieving applicants - with more individual scores available on the SAT, it is easier to pick between 2 similar applicants. because the ACT’s scores are fairly broad (a 36 on the ACT corresponds to i think a range of 2370-2400 on the SAT), it is less useful to the most prestigious universities.
@normanxi Has this been confirmed by anyone who actually works in admissions itself?
Some schools may prefer one over the other based on the nature of the tests; SAT is said to tend to test more problem solving, ACT more acquired knowledge.