My favourite is definitely Fly Buys, I am not the average consumer so most of the loyalty cards just don't add up to anything for me. But grocery shopping is something I do regularly and I have earned movie tickets, a magazine subscription and cash off my groceries in the past couple of years. It's great!
Whilst I mostly shop there in the sales, I really like my Myer card, particularly now I get points when I fill up at my local Caltex/Woolworths petrol station.
I'm also a big fan of the Everyday Rewards card with Woolworths and I save up my points for vouchers at Christmas.