CP, then AC pretty much exclusively till a little over two years ago when I discovered United flew the same transborder and overseas routes at half the price.

Said buh-bye to AC last year and went with Delta for transborder, and DL/KLM/KE for my overseas travel. I bite the bullet on domestic and use WS ... no real FF program there, but they're generally cheap enough my savings constitutes enough of a reward.

I still like AC, and as a Canadian citizen I would prefer to support a Canadian business ... but they're simply no longer competitive. Nice product, but not worth the considerable premium.