With Aeroplan having so many 1:1 transfer partners, it seems like there should be a ton of churning opportunities to rack up some massive welcome bonuses. For people such as myself with addresses in both Canada and the US, there are even more cards that could count.

Any recommendations for particularly attractive (high welcome bonus, low annual fee) cards that grant either Aeroplan points, or points that can be transferred to Aeroplan? Suggestions for both Canada and the US are welcome.