Most online businesses I access have multiple payment modes, two of which (them being the ones I can use) are debit cards and online banking. Choosing the latter takes you to your bank's online portal, where you need to login with your account's online credentials and approve payment; I assume this is some sort of a wire-transfer.
In terms of security, both employ an OTP to my phone. I don't know what encryption the card portal's website uses, but I assume it is good. The bank's portal uses: TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384, 256 bit keys, TLS 1.2
As far as I know, under most cases (online retail), no extra charge is levied on either of the modes (some websites do: espescially travel).
One advantage I see with using the debit card is that I can accumulate reward points with it.
I want to know if there are any other reasons I would want to prefer one method over the other.