Personally, what I would do is:
Look at the 1st table on link detailing the cents per point for each card. You want to find a low one (cost less to ‘buy’ points - which in this case it is equivalent to your buying points). If you already have a card that give you the ability to ‘buy’ point cheaper than you threshold (maximum cost you are willing to pay for your points), you can use that card to pay the ATO and in the process earn/‘buy’ points.
If you don’t have a suitable card, consider getting one. Card choice/payment method all depends on how much you are willing to pay for points, how big your tax bill is, etc.
True for most circumstances (this included)->>> The best card for you may be different to mine and the best card can always change as time goes by.