Considering your primary usage is in the city, a CVT gearbox is a better option than a DCT. DCTs can be jerky in stop-and-go traffic and are prone to overheating, which results in more frequent wear and tear. With that in mind, the Hyundai i20 CVT would be a better choice for you.
This Hyundai car is easy to maintain and comes equipped with most of the features available in the segment. Its CVT is also one of the smoothest on the market. The i20 has a larger wheelbase (2580mm) compared to the Tata Altroz (2501mm), translating into better second-row space. The engine is refined, and the power delivery is smooth, making it an overall easier car to live with.