Both cards have limits. My suggestion is to have both of them. 1. For miles calculation. We usually didn't think about the spending block. Which UOB has the block in $5 and CITI is in $1. To simplest the usage. You can use CITI to pay any bill which under $20. And use UOB to pay the bill over $20. You can refer to this chart. And here's the formula if you need. UOB=INT(INT(amount/5) 3.5) 2 , CITI=INT(INT(amount) 1.2) ! 2. UOB Amex has a benefit which gives you 20,000 miles every year with $50,000 spending which is the most important attraction to me. The maximum rate under this benefit becomes 1.8miles/dollar. And that's why I apply this Amex one rather than visa one. 3. Amex channel has a lot of limitations which you can not use it to pay tax, telephone bill or insurance(I'm not sure). But to be honest. Citi also changed their policy on Oct 2018 which you can not earn any points from insurance or electric wallet top-up. So if one card has no benefit from certain category spending. Please just choose the other card. Or the rebate card. 4. For the redeem. If you can not earn points very fast. Please choose CITI or even DBS altitude. Their points never expired. Or just use the rebate card which may even better for you. If you can earn points fast. UOB's two-year limit will not be an issue. 5. KEEP YOUR MILES UNDER ONE AIRLINE! Now airlines have different alliances. So use one airline account to redeem different airlines tickets is far than enough for you. Because 1. you usually take SQ. 2. Miles transfer from bank to airlines is blocked in 10k. But your reward ticket uses variable miles. The balance miles always become waste if it's not in your SQ account. Conclusion: No need to consider how many airlines the card support. You only need SQ. 6. Join the miles promotion from CITI. Last year they got 43k miles marathon. This year they have 38k miles activity. Which let you spend 8888 dollars within 2 mths. and pay 288 admin fee to get extra 28k miles. It's not bad. And last year 20X promotion is really good. UOB doesn't have too many promotions. Just the 10miles promotion for Agoda is not bad(have maximum S$1500 limit). But Agoda usually has a lot of rebate for cards which make 10miles promotion not worth. 7. CITI have Priority Pass. UOB doesn't. If you need miles. That means you need lounges. PP gives you the basic lounge access. Better than nothing. You can add Citi to your apple pay. UOB Amex can not. If I can choose only one of them. I'll choose UOB Amex.