I'm very confused between the following options: Maruti Suzuki Brezza, Tata Nexon, Suzuki Fronx, and Tata Punch. I would like to know whether I should opt for a CNG variant.

For the given budget, you will get higher or fully loaded variants of the Maruti Suzuki Fronx and Tata Punch, compared to mid- or entry-level variants of the Brezza and Nexon, which are larger. So, you need to choose whether you prioritise features or a larger, more premium driving experience.

Between the Maruti Suzuki Brezza and Tata Nexon, both are very competent offerings, although the Maruti will be more efficient and slightly easier to maintain. Opt for the CNG variant if your usage is high (only then will you benefit from its lower running costs) and if boot space is not a major concern.