Which one is "better?" Do you need both? Do you have to take the standardized test?
Technically, there is no "better" one. Both are stardardized tests accepted by colleges, and colleges do not value one over another. But since the two tests are quite different, there is no need to take both, and it's critical to take the one that fits you better.
In other words, you want to find out which one is easier for you. Here are some differences between the two:
It's confusing, isn't it? A better way to determine which test works better for you is to try a timed full-length diagnostic test for each and use a conversion chart to compare the results. If your results are very close, then you need to "feel" it.
But you are probably aware that you may not need to worry too much about these tests. Indeed, the pandemic has changed the entire landscape of the college admission, good or bad. And now, there three different testing policies:
Test-Blind: The college will not use SAT/ACT when making decisions. They may use it to validate classes, but that's it. The test score, high or low, has no impact on your admission result. A typical example--the University of California.
Test-Optional: This is the more common policy nowadays. Basically, you make your decision. If you submit it, colleges will consider it as a part of your application; if you don't have it, they will still review your application. While having a competitive score may give your bonus points, not having one does not put you at a disadvantage, accoring to colleges that adopt test-optional policy.
Test-Mandatory: Yes, like the old times, you have to submit SAT/ACT with your application. We have seen many colleges go back to their old policy in the past two years, starting from colleges in Florida and then Georgia Tech, MIT. Are there gonna be more? Definitely.
After all, whether you should take a test or not depends on many factors: the colleges you are applying for, the major you are interested in, and your readiness.