Best mobiles under 15,000₹

This phone is durable and comes with everything you need and might require in future. Only thing it lacks is the support for NFC. But the rest of the features of this phone makes that negotiable.

Check out full features list on GSM Arena here: Moto G Plus, 4th Gen (Black, 32 GB) Specifications

This is one phone you can buy with eyes closed and expect to perform over time. Plus the trust of Amazon.
Buy it from Amazon here: Moto G Plus, 4th Gen (Black, 32 GB)

2. Xiaomi Redmi Note 3 Price: ₹ 11,999

I will this phone as an answer to Moto by Xiaomi.
People don't easily trust the Chinese companies when it comes to technology. But Xiaomi has built up their reputation over the time. This phone is cheaper and features everything as Moto G4 Plus and more. 

Buy it from Flipkart here: Redmi Note 3

Also mind that the Dark Grey and Silver versions of this phone is coming soon here: Redmi Note 3 Black

Redmi Note 3 Silver

3. Mi Max (Gold, 32 GB) Price: ₹ 14,999

This is one elegant phone with a huge screen and every other feature previous phones had.

This beauty comes with an overkill RAM of 4 GB which I don't think you would easily be able you consume. But who knows. Android Applications sometimes take up unnecessary space and tends to slow down the phone.