Of the two cars you've suggested, and given your requirements, we would recommend the new Kia Seltos. 

For one, you'll find it a more natural upgrade from your Hyundai Venue 1.0 Turbo DCT, as both cars come from the same Hyundai Group family and use related hardware. That being said, the Seltos is built on a new-gen platform called K3 and comes with far more advanced tech. Especially when it comes to the infotainment system and connectivity. 

Because the Seltos engines are unchanged from before, we know what to expect from them - whether the 1.5 naturally aspirated petrol or the 1.5 turbo petrol. Since your driving is 60% city, we would stick with the 1.5 petrol IVT, as it is the smoother and more efficient powertrain overall. 

Kia, like Hyundai, tends to be reliable in the long run - as you've no doubt seen with your Venue - and maintenance costs are reasonable too. The Tata Sierra has promise, but its all-new engines are as yet unproven, and in our experience. While its 1.5 turbo petrol is smooth and powerful, the 1.5 naturally aspirated petrol feels underpowered in this size of car.

The new Tata Sierra has a strong air conditioner that cools its large cabin rather quickly. This is despite its large glass area, created by its huge panoramic sunroof. This is true of the second row, too, where the upward-tilted central AC vents do well to direct air to passengers. 

Rear seat passengers have class-best space and comfort, too. Thanks to the immense leg room, headroom, and width. The Tata Sierra has a large boot as well, which will easily take a full-size golf bag.

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.