It depends on your usage.
Mastercard: Dining & Online
Visa: Entertainment & Departmental

Mastercard gives cashback for Online and Dining spends.

Visa gives cashback for Departmental and Entertainment.

So it depends on how you normally spend loh. Take note that both not entitled for groceries.

Call CS to cancel the card that you don't wish to keep/use.

if you plan to join the spend now 4 more CB campaign, then you should keep the Quantum Visa after you finish 10 X RM60 for Quantum MasterCard as you will get additional VIP points for Quantum Visa for non entertainment/departmental swipe and additional CB if you swipe for movie or departmental.

Let say one month got 4 weeks, you need one week fully for Quantum MasterCard to swipe 8 X RM60.
2nd week 2 X RM60 for QMC and 6 X RM60 for QV.
3rd and 4th week will be 8 X RM60 for QV.
If got 5th week then will be another 8 X RM60 for QV.
Let's say for the current campaign which starts from July till Dec, there are 26 weeks.
Means you got 60 swipes are QMC while the remaining 148(26 X 8 - 60) swipes are QV.
148 X RM60 earn you 8880 VIP points and thats around RM22.20 value if you exchange RM10 voucher for 2000 VIP points.
If you combine the early campaign this year which is RM500 X 2 swipes per week, you got 12 swipes for QMC and 40(26 X 2 - 12) swipes for QV.
40 X RN500 earn you 20000 VIP points which is around RM100 value in voucher form.
That not bad for additional RM122.20 bonus to cover the SST and the SST might be waive for yearly RM8000 spend for each card.
Of cos if you manage to get Visa Infinite, then Quantum Visa can cancel already as VI got 0.3% CB straight into your card, not VIP points.