Bottom line...
IF you can get right to work in the US, the airline employment opportunities here will far exceed those in Canada for someone of your age. Even if you like living in Canada, you still do that and commute to work at any of a number of northern US pilot bases.
In the US, in the current hiring climate (which should last 10-15+ years), you do not need any relationship with a regional, you essentially get to pick the one you work, except that ones owned by AA which offer flow to AA are a little more picky.
I would think that the first thing you need to do is decide where you want to live and work long-term, and then select a school accordingly.