The Kia Syros is a great option for you due to its spacious cabin and backseats, which recline for more comfort. Furthermore, its boxy design enhances the sense of space inside this cabin. Another good, spacious option is the Citroen Aircross X, which is a large car for compact SUV money. If you have a Citroen showroom near you, it is worth considering.
 

The Citroen Aircross X AT is a good SUV with a crucial USP being the extra set of seats in the third row. It isn't a 7-seater but more of a 5+2, which means the third row is good enough for kids and short adults for quick city drives. 

You can also remove the seats entirely and use the space as a big boot. The turbo-petrol engine is responsive and nice to drive, the ride is extremely comfortable, and it has a decent feature list too. If you want maximum practicality, the Aircross X is a good choice. 

The other option worth looking at would be the Kia Syros. The Syros has an unconventional design, but is excellent when it comes to space and packaging. It also has a higher level of quality throughout the cabin. Sure, it does not have an extra set of seats, but it has a spacious rear seat that gets ventilation for the base and a good degree of recline, too. 

Also, Kia's network is more widespread than that of Citroen, and that does help when it comes to after-sales and service.  

Considering your requirements, the Kia Syros fits the bill and will offer everything you need in one package. 

The petrol engine has enough grunt for daily city driving, and the DCT gearbox is easy to use, especially if you’re not expecting high performance. The drive modes also help it adapt better on highways. It has the roomiest cabin among the SUVs you’ve mentioned.

The rear seat with the recline function is very comfortable. The panoramic sunroof brings in a lot of light and makes the cabin feel more open. The features and equipment list are excellent, and the overall build quality is very impressive.

The only area where it may fall slightly short is fuel efficiency, though the difference isn’t much.

Overall, it’s a fantastic package and works as a great all-in-one car.

The XUV 3XO you have shortlisted is a sub-4-metre SUV, but don't rule it out as it has a wide and spacious back seat. 

In fact, the Maruti Suzuki Brezza, which is also a sub-4-metre SUV, also has a wider back seat and more headroom than its larger siblings, the Maruti Victoris and Grand Vitara, while having the same petrol engine and 6-speed AT.

What's more, you will get a fully loaded Brezza ZXi+ AT for the same price as a lower spec Victoris VXi AT, and within your budget of Rs 15 lakh, on road. 

If you're fine with Kia as a brand, and don't mind the polarising exterior look, the Kia Syros 1.0 T-GDi HTX DCT is an excellent option in your price range, with superb interior space.