Asked on 08 Dec 2020
My monthly spendings are about $800 - 1k, though I'm trying hard to cut down on spending.
Allocation of my spendings: $190 insurance, $90 phone bills, the contract will be ending in 3 months, I will be changing to a plan which will max cost $40. The rest of my spending is for shopping, dining (incl food deliveries), occasional groceries, and transport (ezlink auto top-up). 1 - 2x a year I will sign up for beauty treatment packages that cost 500 - 2k
Not sure if you're still pondering over this, but here's my take on this:
Given your spending breakdown, you have about $600~$800 that will be eligible for rewards (because insurance payments are typically excluded).
This puts the Citi Cashback card out of the picture, since it requires a monthly spending of $888, and the cashback are on very specific categories (petrol, groceries, dining).
Between SC Unlimited Cashback and OCBC Frank, I'd say it depends on how committed you are to cutting down on spending. This is because OCBC Frank has a monthly minimum spending of $600, which based on your breakdown, you are just hitting. Trying to meet this monthly spending may conflict with your goal of trying to cut down on spending, which is not what using a credit card should be about - it should complement your lifestyle.
SC Unlimited Cashback will serve as a fuss-free way for you to get some cashback without having to worry about meeting any monthly spend.
You can also consider some alternatives to the SC Unlimited Cashback, such as the AMEX True Cashback and the Citi Cashback+ card. The former is very similar to SC Unlimited Cashback, but also offers cashback on GrabPay top-ups. Meanwhile, the latter offers a marginally higher cashback of 1.6% vs 1.5%.
Hope this helps!