I know something similar has been mentioned on FT before for Aeroplan -> BAEC before during the Avion -> BAEC 1.5x promos, but considering the recent and future Aeroplan changes w.r.t. charging YQ, the current Avion -> AAdvantage 1.3x promo (ending soon) and AAdvantage's impending change of their MM program, I thought it was worth repeating.

You can currently transfer Aeroplan -> Esso Extra using points.com, then Esso Extra -> Avion -> AA. In the end, you should get ~9 AAdvantage miles for every 10 Aeroplan miles.

Aeroplan -> Esso Extra has a 15K minimum, 50K maximum. Esso Extra -> Avion has a 2500 minimum, 500 increments, and Avion -> AAdvantage has a 5K minimum.

Not suggesting this is the best decision for everybody, but it is an option to consider.