I am based in eastern Canada-YHZ. I usually fly twice a year YHZ-BKK and once a year to Europe. I normally book discounted Business or Premium Economy fares. I have little or no domestic or trans border (USA) flying. YHZ is served by DL. AF/KL serve YUL and YYZ so to fly them requires a connection on a non ST carrier.
Because the Cdn market is dominated by *A, most of my flying is with AC or partners. Recently, through Expedia, AF/KL in combination with CI have been offering very good prices on business class from YHZ to BKK. DL is also an option to Asia via the Pacific. AF is often less than AC for Premium Economy to Europe, The question is of course which ST plan would be best for my travel pattern.