yea it depends on you as a student because subjects you're naturally good at will take less time and effort and you'd still get amazing results. for the same subjects, another student may need to put in more time and effort to produce the same outcome. but for the sake of answering your question, I'd say Maths ext 2, Maths ext 1, chemistry/biology, physics, English advanced (maths ext 2 taking the most effort/time, English advanced taking the least)
but honestly I'm not even convinced by the way I ranked these, it really depends on the student