Without knowing your specific requirements, it is hard to give a definitive pick. Broadly speaking, however, the Mahindra XUV7XO diesel AT is the more powerful and exciting choice. 

Its 2.2-litre diesel engine's 185hp and 450Nm are significantly higher than the Kia Seltos' 1.5-litre diesel's 115hp and 250Nm figures. The XUV 7XO diesel feels more effortless, especially on highway drives where the Seltos feels just adequate. 

Both models do use smooth torque converter automatic transmissions, but it's the Mahindra car that is more responsive and quicker to shift to. 

The recently-launched Mahindra XUV 7XO is a good option to consider. It replaces the XUV700 and gets interior and exterior changes, along with more features. It is spacious, comfortable and has a strong set of engines. 

The 2.0-litre petrol is smooth and refined, and the 2.2-litre diesel is punchy and relatively efficient. You also get the added practicality of a third row of seats, which the Kia Seltos and Tata Sierra don't get. Mahindra XUV 7XO price range from Rs 13.66 lakh to Rs 24.92 lakh (ex-showroom, India). 

Between the diesel Mahindra XUV 7XO and the electric XEV 9S, we think you would be better off with the XUV 7XO since your main purpose of the new car is to go on family trips. 

Highway charging infrastructure is still developing, and quite a few times, existing chargers are either occupied or not operational. 

Thus, if your trips are over 300 km long, you would need to stop and charge. This will ensure you can make it back or even have sufficient charge to drive around when you get to your destination.

Moreover, if these trips involve hill climbs, you will lose battery charge much faster. Conversely, the diesel Mahindra XUV7XO will be just right for these conditions. The torquey engine is powerful enough to tackle climbs, and with diesel being the fuel of choice, there will be no range anxiety.     

With your budget set at Rs 17 lakh, we would advise you to go with the new Kia Seltos as it is a great all-rounder. Also, you would get a mid-spec car like the petrol manual HTK(O), which, besides the basics, would also get you a few niceties. The petrol engine is also a good performer, delivering a good blend of performance, refinement and efficiency. 

The lower spec Tata Sierra, on the other hand, will come with the 1.5 litre naturally aspirated engine. It is a very sluggish performer, and while the Mahindra XUV 7XO will deliver on this front, it would not be as efficient as the Kia.         

The Mahindra XUV 7XO is a well-rounded product, and the AX7 T is the variant to choose as it offers all the premium features you would expect at this price point. You get a 16-speaker Harman Kardon sound system, ventilated front seats, Level 2 ADAS, an electronic parking brake and much more.

As for whether you should opt for AWD, it really depends on your usage. If you live in the hills or regularly drive on challenging and slippery terrain, the AWD version can make sense. For most driving conditions, however, the Front Wheel Drive version will do just fine.

If your idea is to get into serious off-roading, the 7XO is not the best choice, even with AWD. For that kind of usage, the Mahindra Scorpio N or the Mahindra Thar Roxx, with higher ground clearance and a low-range gearbox, will be far more capable.