Some options you can consider are the TVS Apache RTR 310, KTM 390 Duke, Triumph Speed 400 and Royal Enfield Guerrilla 450. The Triumph and Royal Enfield aren't as overly sporty as the other two and will have a more effortless riding experience owing to their torque delivery, which is earlier in the rev band. 

The KTM 390 Duke is a proven product when it comes to sheer speed, but in its latest avatar has become quite compact, which may not be the best thing if you are a larger person. 

Last but not least, the TVS Apache RTR 310 has great handling and reasonable performance. We would recommend getting the variant with the quickshifter on the TVS as that offers the best value for your money. 

Take a test ride of everything you're considering before you decide. 

Both the bikes you have mentioned will fit the bill for your use case. However, both the Triumph Scrambler 400 X and the TVS Apache RTX 300 have tall seat heights (830mm or more), and for a new rider of your stature, they could feel like a little too much, especially at slow speeds and during off-roading. We would strongly recommend a test ride of both before you decide to go ahead with your purchase. 

If these two prove to be too tall for you, something more street-biased (and crucially, lower) like the Triumph Speed 400 or Apache RTR 310 from these respective brands would be a good fit. 

Among these two, the TVS Apache RR310 is the more modern and feature-packed motorcycle, making it more value for money. The Kawasaki Ninja 300 has not received any major updates in a long time and carries a higher price tag. The servicing and spare parts of Kawasaki will also be priced at a premium, so that is something to take into consideration. Two other bikes you can also check out are the KTM RC 390 and the Yamaha R3. Take test rides of all four bikes so you know which one suits you best.

If you want your new bike to be sporty and compact, then bikes like the KTM 390 Duke, TVS Apache RTR 310 and Honda CB300R would be our recommendation. 

If you want to have a machine that's capable of doing longer distances with luggage and/or a pillion, then an adventure bike like the KTM 390 Adventure (either of the 2 variants will do) or the Royal Enfield Himalayan 450 will fit the bill. 

Before pulling the trigger, try to get long test rides of every bike you are considering to make an informed decision.