The choice really comes down to your usage and what you value in the car. If you need more space for both passengers and luggage and have a few long drives that you would undertake, then opt for the Tata Sierra. It is a much larger car and has a very spacious interior.
The ride quality is also very good over both bad city roads as well as high highway speeds. If, however, your usage is mainly going to be within the city, then the Kia Syros is the better buy. Its compact footprint will be much easier to manage while driving congested streets, and finding parking would be easier. You would also enjoy the top variant and its features.