Of the three bikes you've shortlisted, the Triumph Scrambler 400 X will be the best all-rounder and will also be very easy to ride inside city traffic with its tractable engine and short gearing. 

While the RTX 300 has slightly better suspension travel and composure, it is still a new product, and it would be advisable to wait some months before buying an all-new machine like this, so if there are any teething issues, they can be ironed out. 

If you are open to having a retro riding experience, then the Royal Enfield Bullet / Classic 350 are worth looking at. These are very comfortable machines, although their performance won't be anywhere close to as sprightly as the other bikes you're looking at. 

On the plus side, the Bullet/Classic are much more affordable to purchase. 

We'd recommend a test ride of the RE 350s before you make a decision. 

Since you haven't specified what style of bike you want, nor given some details about your physique, recommending something concrete will not be possible. However, we'll give you a variety of options to choose from, spanning multiple classes. 

In the neo-retro space, you can look at bikes like the Royal Enfield Classic / Bullet / Hunter 350, TVS Ronin, Triumph Speed T4 and Honda CB350 models. These will have a relaxed riding experience and a plush, comfortable ride quality. The Speed T4 will be the quickest and most responsive of them all, but still very manageable for daily use.

If you want something sportier, the KTM 250 Duke makes for a compelling option for your one-bike garage. 

If you're leaning towards the more adventurous side of things, then the Hero Xpulse 210 and the TVS Apache RTX 300 are the way to go. 

It would be advisable to take test rides of all of these bikes to see what style you prefer and which bike you are most comfortable with. 

In the 350cc space, bikes like the Royal Enfield Hunter / Classic / Bullet 350 and Honda CB350 trio make for good options considering your mixed usage. All of them have upright ergonomics, comfortable suspension setups and decent fuel economy. 

If you are open to waiting for a few months, Bajaj will be releasing 350cc versions of all the Triumph 400cc bikes. These will offer you noticeably more performance than the aforementioned air-cooled 350s while being priced similarly. 

Between the Royal Enfield Classic 350 and Meteor 350, the former would be our recommendation. The Meteor's feet forward position will transmit more jolts to your back over bad patches of road. Therefore, it won't be comfortable over long stints in the saddle. The Classic's upright and neutral rider's triangle will be easier to live with on a day-to-day basis. 

You should also take a good look at the Honda CB350 models because they have a similar riding experience to the RE 350s. But are much lighter and come with alloy wheels and tubeless tyres. They also have a slip/assist clutch, resulting in little effort when operating the clutch. 

Since you are a taller person, looking at an ADV like the Hero Xpulse 210 and TVS Apache RTX 300 is also a good idea. Of the two, the RTX is the better all-rounder, but the Xpulse is lighter.

Take a test ride of these bikes so you can decide which is a better fit for you. 

For city use, we'd recommend picking between the Royal Enfield Classic 350 and Honda CB350RS. Both seat the rider comfortably, although the CB350RS has a slightly sportier seating position. But also have a comfortable suspension, which is what you'll value in the city. If ridden sensibly, the two 350s will also return decent fuel economy. Do bear in mind that the Classic 350 is likely to be updated with a slip/assist clutch soon. if you are looking to buy this bike, we'd advise you to defer your purchase by a few months.

Since you're already looking at the Classic, its sibling, the Hunter 350, also makes for a great city bike. Despite its relatively smaller size, larger riders will fit just fine on the Hunter, and this is the most city-friendly machine of all the bikes you are looking at. 

The Harley-Davidson X440 is also a good option inside the city with its torquey engine, neutral ergonomics and decent suspension. But its fuel economy will be lower than the other bikes, and its top model falls outside your budget.

Take a test ride of these bikes to decide which is the best option for you.