Initial bonus points, faster accrual during an introductory period, different earnings rates for the same account and redemption rates with the potential to turn what looks like a good offer into an absolute dog - it's enough to challenge even those with the finest minds for puzzles.
Let's start with three cards attempting to lure you with introductory offers. You can get 5000 frequent flyer points just by signing up to Westpac's Altitude Amex card, double points until November 30 with Westpac's Amex Earth card or 1.5 points for every dollar you spend until January 31 with NAB's Ant Amex card.

All three cards cost $100 a year or less (Altitude $100; Earth $49; Ant $99). All three ordinarily give you one frequent flyer point for every dollar you spend (uncapped). And all three allow secondary cardholders at no extra cost.

But they are certainly not created equal. Here, we will ignore interest rates on the assumption that you make credit card transactions purely to earn frequent flyer points and pay off your balance in full each month (but if you're interested, Earth has the best at 12.48 per cent; the others are about 18 per cent).

For starters, the Westpac Altitude Amex card carries a maximum of 45 days interest free, which is less than the standard 55 days.
And don't be fooled by the 'two reward points for every dollar you spend' - to get one frequent flyer point, you have to redeem two reward points. It is a one-for-one card in this respect. Points are, however, valid on airlines other than Qantas.

Westpac's Earth Amex card offers the full 55 days interest free, but look out for the "special" 5.99 per cent interest rate when you buy eligible services from Qantas - there are no interest-free days so the rate applies from day one.

Finally, NAB's Ant Amex card has only 44 days interest free.
Financial services researcher Cannex says that with all of the above cards, a free return trip from Sydney to New York would require a spend of $128,000.

However, you probably noticed that they are all Amexes (the Altitude and Earth schemes also come with a MasterCard, but this attracts points at half the rate). Not only is Amex not accepted everywhere, merchants sometimes levy an additional fee on transactions.

For this reason, it might be worth considering the Citibank Silver Visa or MasterCard. This card also gives you one frequent flyer point per $1 spent (i.e. $128,000 to New York), the annual fee is a competitive $69 and you get up to 55 days interest free (the interest rate is 18.99 per cent).
Just bear in mind that the number of points you can earn is capped at 40,000 a year.

It is possible to earn as standard more than one point for each dollar you spend, cutting the New York trip to as little as $85,334 - but you pay for this through an annual fee as high as $395.

Sign up to a card that gives you fewer than one frequent flyer point per $1 spent, though - for example, the Westpac MasterCards mentioned above, a standard CBA card or ANZ Rewards Visa - and that return flight could cost you as much as $287,986.