The key is the ability to buy seats yourself so that you can take advantage of seat sales. I redeemed my points on a flight to Asia and it was actually stupid to do so as a flight could have been had cheaply.
Cashback greatly exceeds anything you get with respect to points, and offers way more in terms of flexibility, usability, and access to seat sales. At least for the main two (Air Miles / Aeroplan) cards. The TD Infinite cards that let you apply cash towards flights charged to the cards have the opportunity to be quite good - might want to look into those.
My AMEX is 2% cashback on everything, no fee, no cashback limit though being AMEX it's usability is limited to major stores.For everything else most RFD'ers are using a MBNA SmartCash card:
http://forums.redflagdeals.com/mbna-...ash-mc-722828/