Well Captain America was first published in 1941 and the Emma Peel Avengers didn't start until 1961. So Captain America was first.
Canada is America's hat, we're on top. If it was prison America would be our b_tch, because we have the top bunk. (I'm just joking, don't take this the wrong way. I don't want to start an international incident.) Also the Canadian Dollar is worth more than the American Dollar is so maybe they are trying to make more money.