I think both are good options:
- With engineering, I think overall careers would depend more on the focus of your studies. The main engineering disciplines are chemical, civil, electrical and mechanical.
- Actuaries can work at top accounting firms like the Big Four (PwC, Deloitte, EY, KPMG) for example.
In addition to your mathematical ability, you should consider which field you are more interested in and feel is the right one for you, which of course will require time. I doubt you will be able to make a final decision this early. The closer you get to your HSC, the more informed your decision will be.
I hope this helps!