What are the best miles cards for online spending?

For online spending, consider getting the following

1. DBS Woman's world card- 4 mpd (miles per dollar), capped at $2,000 per month- you don't need to be a woman to get this card!
2. Citi Rewards Visa- 4 mpd, capped at S$1,000 per statement month

3. OCBC Titanium Rewards- 4 mpd, capped at S$12,000 per year. this is better if you're buying a one-shot big ticket item, as the cap is applied per year rather than per month. You can get both the Blue and Pink version of this card to double your cap

do remember that certain exclusion categories apply (eg insurance, government payments), so be sure to refer to the T&C. Refer to this guide for more details on what card to use where: https://milelion.com/credit-cards/guide/