Between the three cars you have shortlisted, the Tata Sierra Adventure Plus is the nicest, especially because of its turbo-petrol engine and torque converter (automatic) combination. Its powertrain will feel smooth, refined and powerful, good for city and highway driving, both. 

The Kia Seltos turbo's dual-clutch automatic can feel a bit jerky at low speeds or in bumper-to-bumper traffic conditions. If your usage is mainly in the city, opt for the 1.5L petrol-IVT instead, which is a far smoother option. 

Since you have the budget, and don't mind opting for a larger car, we'd rule out the Mahindra XUV 3XO as the Sierra Turbo-AT or Seltos 1.5 Petrol-IVT deliver a more premium overall experience.

Yes, the Tata Sierra will meet your requirements of safety and comfort very well. In terms of active safety, the Sierra has good grip around corners and good high-speed stability, too. The safety equipment is also elaborate with 6 airbags, electronic stability program (ESP) and after-impact braking standard across variants. 

The Sierra is yet to be tested at either GNCAP or BNCAP; however, Tata Motors says the car is designed for a good rating and given the company's track record, this should be the case. As for comfort, the ride quality is good, and there is ample space inside. The seats, too, are comfy and at the rear, there's enough space for three to be seated in comfort. 

Your observations are correct. Neither the Tata Sierra nor the Kia Seltos has been crash tested by Global NCAP or Bharat NCAP yet. But Tata Motors cars have had a good track record with these tests. While the Kia Seltos uses an all-new global platform that should be safer than the outgoing model.

Both SUVs feature the latest in active and passive safety features, which should be a reassurance, and thus, on the safety front, you won't be wrong to go with either. As for other factors, the Sierra is certainly the more spacious of the two and edges the Seltos out on comfort as well. 

However, in most other areas, it's the Seltos that comes out on top, including, as you have pointed out, after-sales experience. The Sierra is being produced at the ex-Ford plant in Sanand, Gujarat. It is said to have higher manufacturing standards, and the brand has been committed to improving its after-sales service across the country, but the results of that will take some time to show.

If you are looking for an SUV with a good luxury feel, we would recommend that you look at the compact SUV segment instead of the mid-size market. While you will get mid-size SUVs for under Rs 15 lakh, they will all be the lower variants, which will not look or feel very luxurious. 

The best options here would be the Kia Seltos and the Tata Sierra. However, as we mentioned, if you do look at a segment below, you could get a Hyundai Venue, which has a very premium cabin in both look and feel and will be very well equipped too. This is the SUV we would recommend to give you that luxury feel at your price point.  

The Tata Sierra is the most spacious and comfortable option here, and it also has a punchy turbo-petrol engine and a feature-rich cabin. The Honda Elevate is a good option too, with a refined naturally aspirated petrol engine and a smooth CVT gearbox. But does not have the tech or space of the Sierra. 

The new Renault Duster will soon be launched in India, and we will get a first glimpse on the 26th of January. The Duster is a strong brand name and is definitely worth waiting for, so we would advise you to halt your purchase a little while longer.