From what I gathered when I was in your position (I'm in Year 11 going through VCE now) it's best to lean more towards a tertiary degree/qualification outside of aviation so you at least a) have something to fall back on should you not pass a medical down the track and b) you can use it in a job to finance a CPL/ATPL before you start.
Maths and Physics definitely, otherwise you'll be asking yourself "what if?" when you didn't get into the course you wanted later on.