If you'll be doing travel spends then also consider Axis Atlas along with Amex Trifecta (MRCC+Gold+Plat Travel)
HDFC Infinia would also be good card to have if you have existing relationship with them and get cards like DCB with high limit which can be later upgraded to Infinia.
Platinum...
Well that's good to know, but I'm just telling my experience, which I stated is very limited and I'm not claiming it as a fact. Its anecdotal and I might experience rejection more as I amex cards offline.
I have had heard this since forever but my experience is opposite of this strangely. I am using amex in teir 2 city and its been never rejected by a merchant just because its an amex.
If a merchant accepts credit cards, they've always accepted amex too in my case although my experience is...