I’d say it’s up to you. In general, biology is pure memorization, but they ask all the details and questions are usually tricky whereas chemistry is less memorization (at least for me), there is not as many things to learn, you just have to understand. There are not many calculations for SL either, most of the formulas are present in data booklet. Honestly my tip would be just google for chem and bio guides, read them and decide which interests you more. And if you decide to study psychology and take it HL, some unis require one science HL as well, so do a little bit of research on that!