Since your priority is third row space, it would come down between the Maruti Suzuki XL6 and the Kia Carens Clavis. The Hyundai Alcazar does have a third row, but it isn't as roomy as the other two. 
The Kia Carens Clavis has the edge when it comes to features and equipment, a plush cabin with a premium feel and a more powerful engine.

However, the XL6 is an excellent value considering what it offers for the price. If you seek performance and features and don't mind paying extra, the Clavis is a very good choice.

However, if you can make do without the jazzy interior and want a predominantly spacious third row, the XL6 would be a good choice. 

The two cars you have shortlisted fall in different segments; in fact, where the Maruti XL6 price ends, is where the Hyundai Alcazar price begins. The Alcazar is a superior vehicle in terms of comfort, quality, features and engines. 

However, the XL6 MPV body style means that space efficiency on the interior is better. The XL6 has just a single engine option - a 1.5-litre naturally aspirated petrol with a 5-speed manual or 6-speed automatic gearbox. 

Also, it is not as powerful as the Alcazar, but it will be more fuel-efficient. If you are budget-conscious and want to keep running costs low, the Maruti XL6 is the better choice for you. You could also consider the Kia Carens Clavis, which falls between these two on price.

Maruti Suzuki has not confirmed any plans to launch the XL7 in India. The current XL6 is a 6-seater, so it won’t meet your requirement.

In either case, the Kia Carens Clavis diesel is the superior MPV. It has a nicer, more practical interior and comes with a long list of features. The 1.5-litre diesel engine also offers stronger performance, and you will feel the benefit of the extra power when the car is fully loaded with passengers.

Looking at your criteria of safety and comfort, along with an automatic transmission, we would recommend the Maruti Suzuki Victoris. However, if you want a seven-seater, then the Scorpio N would suit you better of the two that you have shortlisted, as the XL6 does not meet your crash rating bar. However, bear in mind the ride of the Scorpio is a bit jittery and won't be as plush as the XL6 or Victoris. 

Automatic options without a sunroof but equipped with a factory-fitted 360-degree camera include the Maruti XL6 and the Citroen Aircross X. The XL6, being an MPV, offers smooth, comfortable, and the assurance of Maruti’s reliability. What's nice is that ingress and egress is a breeze. with an all-new more (than before) upmarket interior and excellent driving dynamics. It delivers stronger performance, though its fuel efficiency may not match that of the XL6.