Since this is your first bike, starting small and approachable would be the smart way to go about it. In that same vein, we would recommend the new Yamaha XSR155 because it is a light, comfortable, fuel-efficient machine that's also reasonably exciting to use. 

If you want a larger machine, then bikes like the Honda CB300F, Bajaj Pulsar N250 and Suzuki Gixxer 250 would be good options. 

Take a test ride of everything you shortlist before you decide. 

Since you have a commute that has some highway riding, we'll recommend bikes displacing 250cc or more so you can maintain decent highway speeds without feeling the engine is strained. 

There are loads of options in your price bracket, like the Royal Enfield Hunter 350, TVS Ronin, Honda CB300F, Bajaj Pulsar N250, Hero Xpulse 210 and TVS Apache RTX 300. 

Take a test ride of all the machines you shortlist before going ahead with your purchase. 

Since you have had a good experience with a Honda machine, you could stick with the brand and go with the Honda CB300F. The CB300F is light, comfortable, spacious and will return decent fuel economy. If you want to switch brands, the Bajaj Pulsar N250 and the Suzuki Gixxer 250 make for good upgrade options with their smooth engines and comfortable ergonomics. 

If you don't mind staying in the same displacement range while getting a significant performance bump, the KTM 160 Duke and Yamaha MT-15 warrant consideration. With their liquid-cooled engines and light weights, these two will give you the performance step up you want without sacrificing on mileage. 

If you're not going to go on longer journeys often and want to stay in the same displacement range as your Unicorn, the Bajaj Pulsar N160 and TVS Apache RTR 160 4V will serve you well. If you want a small step up in terms of performance without sacrificing too much fuel economy, the Bajaj Pulsar N250, Honda Hornet 2.0 and Suzuki Gixxer 250 will fit the bill. You can also take a look at the KTM 160 Duke and Yamaha MT-15 because, while they have smaller displacement engines, they are liquid-cooled and offer punchy performance with great fuel economy. 

The more laidback Royal Enfield Meteor 350 and Honda CB350RS will definitely feel more special in their riding experience and fit & finish. Also, it will be significantly more expensive to buy and maintain compared to the aforementioned bikes. 

You can consider bikes in the 250cc category, and for your needs, the Suzuki Gixxer 250, Bajaj Pulsar N250, and the Bajaj Dominar 250 should get the job done. 

The Gixxer 250 and Pulsar N250 are good for city commuting with their nimble handling abilities, while the Dominar 250 is heavier and more touring-oriented, making it good for highway runs. 

Do take a test ride of all these motorcycles with a pillion on board before making a purchase.

Since you have some highway usage, we would recommend something like the Bajaj Pulsar N250 or the Honda CB300F.

Both can hold a steady 80-90 kmph without their engines feeling strained. Another option you could look at is the Royal Enfield Hunter 350, if you’re open to owning an RE.

All three are good to use inside the city, although expect relatively lower fuel economy on the Hunter than the Pulsar or CB300F. 

Keeping your requirements in mind, a 250-300cc sporty commuter like the Bajaj Pulsar N250, Suzuki Gixxer 250 or Honda CB300F will be a good fit. All three have modern looks, the required fuel efficiency you desire and will strike a good balance between city and highway duties.