Here are the best smartphones priced INR ~15,000 in India, that offers spectacular long-lasting built quality with future proof features at an affordable price range.
Redmi Note 4:
Redmi Note 4 was launched in India in January 2017. Till today, this device is one of the most anticipated smartphones under the 15,000 price range. The all-metal unibody, combined with power efficient Qualcomm Snapdragon 625 with RAM up to 4 GB and 64 GB storage was introduced by this device. Not to forget its long-lasting massive 4000 mAh Li-ion battery that can last longer than any smartphone in the price range. The Redmi Note 4 is available in both online and offline stores (INR 500 extra on offline stores). The more interesting feature of this device is its software, The MiUi 8 (based on Android Nougat) is one of the fine-tuned customised Android experience available, though the experience is nothing like stock Android, it has its own features that make it great. The camera is the only disappointing thing in this device, the 13 MP rear-facing camera does take good pictures in the natural lightening condition, however, devices like Lenovo k8 note and Huawei Honor 6X easily beats this device with respect to camera performance. This device is one of the first devices to receive Android Nougat update, that packs interesting features like multi-window, picture-in-picture mode, efficient CPU and GPU allocation and what not. The 2 GB, 3 GB and 4 GB RAM variant retails for INR 9,999, 10,999 and 12,999 which makes it a steal deal.
Huawei Honor 6X:
Huawei Honor 6X is the first smartphone that brought dual rear camera feature into the mainstream budget smartphones. This device can take pictures like a premium flagship smartphones. Other than the camera, the device is powered by Kirin 655 Octa-core SoC, paired with either 3 GB (11,999) or 4 GB (13,999) RAM with 32 GB or 64 GB onboard storage. Honor 6X also features all metal unibody that comes in either Silver or Gold Colour. The Hybrid SIM solution also works great, a user can either use two SIM cards or an SD card (up to 128 GB) + SIM card. Both slots support 4G LTE with VoLte capability. The software on the Huawei Honor 6X is a customised version of EMUI based on Android Marshmallow 6.0.1, the OS is heavily skinned and offers few additional features like tap to wake up and gesture recognition. The main attractive feature about Honor 6X is its camera capabilities, Combination of 12 MP + 2 MP can capture great images even in the artificial lighting condition, one can take images with great depth of field and the bokeh effect can be changed after the photo has been captured. The video recording has been limited to 1080p up to 30fps. The only disappointing thing about this device is that it still running on two years old operating system (Oreo is coming on 21st August).
Lenovo K8 Note:
Lenovo K8 Note is the newest smartphone amongst all. The device resembles Redmi Note 4 in terms of design and offers dual camera setup inspired from the Huawei Honor 6X. The built quality is one of the best that anyone can ask for the price tag of 12,990 and 13,990 for the 3 GB, 32 GB and 4 GB 64 GB variant. The device is powered by distinctive Helio X23 10-core SoC, paired with 1080p IPS LCD screen, protected by 2.5 D curved tempered glass. As a matter of fact, Lenovo has ditched its Vibe UI in favour of stock Android, which means the device will now receive faster Android updates just like its Moto family. The rear dual camera setup can capture natural looking photos even in the low lighting and artificial lighting condition. When it comes to the bokeh effect, there is a slight inconsistency in the images produced, a software update is expected to solve these problems in few weeks. When it comes to the day-to-day usage, the device does not disappoint us. The 4000 mAh battery also help the device to last longer without looking for a charger. Lenovo K8 Note does support fast charging (up to 15W) via standard charger that comes along in the retail package.
Moto G5 Plus: 
The Moto G5 Plus is the first budget mid-tier smartphone from Moto to feature the metal unibody design. Moto G5 Plus comes with more prominent 5.2-inch 1080p IPS LCS screen, protected by Corning Gorilla Glass. Under the hood, the device is powered by same SoC that powers Redmi Note 4. The Home button houses the fingerprint scanner that can be programmed into navigation button as well. The another attraction about this device is its camera capability, the 12 MP rear-facing camera with the F/1.7 aperture can take great low-light photographs and videos. The stock version of Android Nougat is one more added benefits to it. This will be the first device to receive Android Oreo update that was mentioned in this post. The device has the smallest battery of the lot (3000 mAh)
Conclusion:
If your main priority is the camera, then go for either Moto G5S or Honor 6X. If you want to stay up to date with your software then go with Moto G5 S or Lenovo K8 Note. If you are into gaming, customisation, extended battery life then, Redmi Note 4 is the one for you.