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.

