If you are not travelling domestic, you are not trapped by Aeroplan.

Join one of the US programes, far better and faster accumulation on work-paid tickets, especially shorthaul. Far superior elite benefits at the mid-tier level.

If you are flying on Air Canada, and will not reach Super Elite - you are best off with Mileage Plus UA.

All fares accumulate 100% elite qualifying miles, award tickets are much cheaper, and status does not have a spend requirement.