From my point of view

+ Aeroplan - the MLL lounges are much better the the AA lounges (not including the AA flagship lounges of course) BUT you can purchase lounge access through other means and get into some of the better lounges.

- Aeroplan - worse availability in my opinion for flights from Canada to US / Mexico and Eruope (possibly on par with Canada- Asia) as AA metal to Asia is very weak. However I am not familiar with using AA points on partners so I may be wrong.

- Aeropaln - much higher taxes and fees on award flights compared to AA.

+ AA at 1,000,000 and 2,000,000 miles gives you status.

- Aeroplan - very weak in how the points expire

+ Aeroplan earning partners gas, other purchases

+ Aeroplan can redeem for Canadian flights not possible with AA

As a Canadian I would put AA much farther ahead, however if all you want to do is redeem for say YVR-YYZ tickets, well you really don't have a choice then.

Also I think I heard a rumor about RBC moving away from AA. Again I am not sure where I heard that so take it with a grain of salt.