If you wanna buy a smart phone and your budget is about 15k then there are hundreds of option . But here are some tips you remember before buy a phone:-
Select the top leading phone brands like MI, MOTOROLA, OPPO, VIVO which would provide you great service and more features under 15000 budget.
Then the camera should be 13 Mega pixel rear and 5-8 Mega pixel front camera.
Now 4G is launched in India so according to internet drains battery fast, so it shoul be minimum 4000 mAh.
Minimum resolution - 1920x1080 with approx.~300 ppi.
Andoid Version - Android 6.0 or Android 7.0.
Processor minimum octa core 1.4 GHz processor.
It should be made of metallic body so it is durable.
Minimum ROM - 32 GB.
Minimum RAM - 4 GB.
so after following these tips you can buy a best smart phone under Rs. 15, 000 budget.
Thank You.