I'm also an AC captive, being now based in YYG. But once I get to YYZ or YUL I also use other airlines for my continuing flights when cost or schedule are better. To add to your list:

BA: The Club World pods in the A350 are on par with AC's signature pods, but with slightly better food and consistently decent service. PE on the A350 blows AC's PE out of the water altogether, especially when the person ahead of you reclines their seat.
KL: J pods on the 78X are comparable to AC's signature product, but with better food, much better service and you'll almost always arrive on time.