Q. Which is best KTM RC390 or Kawasaki Ninja 300

Writing my thoughts assuming you are going to use the bike in city and daily commute.Yamaha R3....Most Reliable, Fuel Efficient, Comfortable, can be used for city commute as well as for touring and has a very linear power delivery. It is little costly than the KTM RC but cheaper than the Ninja. But you can use it as long as you want it in your garage and will give you a better resale price as well. For Ninja, it is not at all reliable, and comes with a lot of maintainence cost - ride it or don't ride! Also its not a VFM machine. It is comfortable and little fuel efficient, but lacks service convenience as compared to Yamaha.For KTM RC, not at all comfortable, it is way too track focused and I assume you don't live on tracks here in India. Not at all a reliable machine and will stay good for a couple of years (can't ignore it's manufactured by Bajaj) and will show its ageing after that with service costs and sudden breakdowns. It is the cheapest sport bike out there in that range, but is certainly not the most ideal chose to make.

Rc390 is fun bike for short rides. But it heats a lot in busy traffic. I do agree with you about service and spare parts of ktm bikes. But if you live in capital cities like the Delhi, lucknow, Mumbai, pune etc then you don't have to worry about ninja bikes too. Ninja will always last longer than ktm. And you will get mob attention too while riding. Ninja is always a premium bike. Enjoy this, it requires handling with care! Also, you would love to see ninja 300 beating Rc390 in terms of top speed

It depents on your riding style and your need ....if you get comfort and power than gp for ninja 300 and if you want tha aggresive posture cool look 373 cc 25 ps raw power than rc is best for you ...