I'm doing FM, Maths, Physics, Chem, CompSci, but that's only because I enjoy STEM
A Level in any subject is very hard, would you want to force yourself under subjects you actually enjoy, and would feel passionate and easier to go through.
Even if you're not going to do it in the future, I don't think universities of that degree type would accept STEM as an advantage in a quite artsy and cultural degree. It's best to do what you enjoy.
Imo Graphic Design is quite good after doing it in GCSE, Media idk.
It's best if your subjects 'speak to each other', not a complete overlap of content, but complement one another, I did Physics and Maths and CompSci for instance, Eng Lit goes well with maybe Law or Government and Politics?
If you want a thoroughly academic AS I'd recommend either Maths or a Science of your choice (Biology is a good one)