Just to confirm you're not looking for credit card then?
If so, I think DBS VISA Debit card is good. Doubles as ATM card as well as for NETS. You get 5% cashback on all paywave, IF you withdraw cash from their ATMs three times or less a month. So depending on how often you withdraw cash, this could work for you.
Personally though, I don't like withdrawing cash from POSB/DBS cos there's usually a (long) queue.
Perhaps rethink your one-card strategy. If you're willing to carry two or three cards, your money can go further for you.