Stan C Ultimate charges 3.5% + GST, but gives cashback of 1.5% on international transactions. Reward rate 3.33%
HDFC Dinners black charges 2% + GST and gives cashback upto 1000 or 1% max if global value program is activated. Reward rate 3.33%
IDFC Wealth charges you 1.5% + GST and gives ~2.35% reward rate
Do these calculations and you have an answer. Amex platinum I wouldn't recommend, but its your call. Other parameters would include milestone benefits etc for card like Dinners black