For what it's worth I like Air Miles. Collecting is pretty effortless since I do a fair bit of shopping at Safeway/Sobeys/Rexall, and I can churn the Amex/BMO cards for more points on top of that. I know some people with pricey prescriptions and they run up a ton of AMs that way.

Nice thing about AM is that flight selection for North America is often much better than for non-status Aeroplan users. For example, using AE to Hawaii is a struggle in finding flights that don't involve overnight in YVR, connection at SFO/LAX, etc... by contrast, Air Miles gets me there the most efficient way.