I used to take the nonstop from SEA-YYZ (in the very comfortable coach section of the A319) back before I became addicted to flying first class. We don't prefer Air Canada for several reasons, chief among them that they do not allow United flyers -- even 1Ks -- to upgrade by any means whatsoever. Secondly, I don't get the 100% status bonus on AC, not do those flights count toward the 10K miles I must fly to qualify for upgrade certs. Thirdly, I have to sit through yesterday's news in French on every flight. Finally, if there is a last-minute change of plans on United they will pull out all the stops for me; on AC I'm stuck.