Do consider your cohorts for Modern and Business. If either of your cohorts are really good, then you should all get moderated up assuming you do great in the HSC. Maybe consider the examination, which ever one you feel you can handle. Consider assessment tasks; I recall there were 3 assessment tasks (and 2 major internal exams) for Modern, not sure about Business, and they were fairly straightforward, so nothing ambiguous. There could be hundreds of factors other than ranks; maybe 5th in Modern is better than a 5th in Business.