I am a boy of 5.3ft height. Which bike will suit me?
Height doesn't matter as much as inseam height. I've seen 5.1 girls and guys riding the KTM RC 390 which has the highest seat height in its class. 800 mm seat height is not a matter of joke. I am 5.7 and after wearing boots its 5.8 and a half and I can maneuver the RC 390 with ease. Your full height with boots would be 5.4 and a half to 5.5 feet which is enough to be riding 750mm+ seat height bikes. For reference just sit on any Scrambler (or Ninja 300) kind of motorcycles. Or if you are from South East Asia you can sit on the Pulsar 220 and the CBR 250/300 and see if your feet reach the ground. If you tip toe, it won't be a problem unless you are dealing with stop-go traffic.
I am 6 feet tall. Which bike is the best suited for me in terms of comfort and reliability?
All the rest of this is nice but look for a standard position bike with enough seat height- A sports bike will just wear your wrists out. Here's a motorcycle ergonomics website that will help you fit a bike to your proportions-Motorcycle Ergonomics