I'm really late to this game. To my fellow Canadians, what is the best air miles credit card out there?

I would prefer one without an annual fee. Not sure if it matters, but most of my miles that I accumulate would be through shopping rather than through air/hotel/rental car useage. My primary airline is AA. I would prefer Visa or MC over AMEX since AMEX is not as widely accepted. I think airline tickets and hotel stays is what I will be using when cashing in miles.

I was considering the BMO air miles card (no annual fee) but it gets 1 mile for every $20 spent. That doesn't seem like a good deal when you compare it to Chase United Mileage that gives something like 1 mile/$1 (with an annual fee).

And is an air miles cc better than a cc that gives cash back (let's say 1-1.4%cash back)?

I would love to get your feedback on best programs (for Canadians). Thanks!