The only benefit of Aeroplan is that you can access VA lounges prior to departure.
As there are no international VA lounges, the benefit is non existent.
Details here:
Aeroplan partners
If you chose singapore airlines via sin you’d get business class check-in, priority boarding, lounge access, extra baggage allowance etc etc.
Economy X can be very expensive. But the regular seat pitch is pretty tight on VA… it feels far tighter than QF. So it *might* be of value.
You might find a better overall package by saving the money from economy X and buying qantas… which then comes with an open bar, meals, and good inflight entertainment, and free wifi while over australia (which is most of the flight!)