When considering mileage as a primary factor for city commuting and short trips, the Suzuki Gixxer 155 may be a good option among the bikes you mentioned. The Gixxer 155 is known for its fuel efficiency and can deliver a decent mileage in city riding conditions. Additionally, it offers a comfortable riding position suitable for urban commuting.
Both the Bajaj Pulsar NS200 and Honda Hornet 2.0 have larger engine displacements compared to the Gixxer 155, which generally means they may have a slightly lower mileage. These bikes are more focused on performance and sporty riding rather than maximizing fuel efficiency. However, it's worth noting that individual riding habits, traffic conditions, and maintenance practices can also affect the actual mileage you may achieve.
To make an informed decision, you could consider factors beyond just mileage, such as overall performance, handling, comfort, features, and pricing. It's also advisable to visit dealerships, take test rides of the bikes, and read reviews from owners or professional riders to get a better understanding of each bike's characteristics and suitability for your specific requirements.