The previous version was written more than 2 years ago and an update is due since there have been some changes to the ez-reload cards. Just a note, Nets Flashpay and Ez-link cards are covered here since both may be used for public transport and both may be top-up using credit cards
As such, the credit-cards that double up as Ezlink/Nets flashpay cards do not offer great perks anymore. In terms of absolute percentages, UOB One is probably the best if you hit the minimum requirements, and there’s no limit to the number of topups you can have in a month. Otherwise, for simplicity sake, then POSB Everyday is the one to put in your wallet.