I do both and am about to the final exams for yr13.
Both are interesting and boring, this depends somewhat on your teachers but coursematerial isn't amazing.
Chem is a lot of basic maths and a lot of content but doable. You do have a learn some specifics that are not sequential but after you get the nack of it it's fine. And there's a lot of past papers to practise on which is extremely helpful.
Latin is split half and half lit to Lang. Lit it about 4000 words of verse which are actually quite good and the commentary notes are interesting as well. About 10000 words of prose which i found incredibly boring as it's all political talk and rumours and the author subtly moaning about random stuff with factual basis, commentary is understandable but boring. Lang is hard coz there's no a2 set text and they are really hard. Espically coz prose translation is boring and verse can go in any direction, very weird and disturbing things occur, for example the text where Ovid teaches men to have more than one women and then his very active afternoon with corinna and her white dress which features briefly at the beginning before being lost to the world. Not particularly fun to translate one on one with a teacher 😂😂😂.
It's your choice and please choose the one you like the best, I think I would've chosen differently if I had the chance again