Buying a bike is depends totally upon the personal choice and taste of the person. It depends upon the riding style which the person seeks. So, I am going to suggest an honest choice from which you can choose.
Sporty(faired) - If you want a very sporty and aggressive kind of bike which is powerful, agile and feels like riding on track then go for YAMAHA R15. But R15 is not for long rides so another option is HONDA CBR 150R.
Sporty(Naked) -Without any doubt go for Suzuki Gixxer.
Cruiser - Bajaj V15, which is pride of legendary INS VIKRANT.
Commuter - Bajaj Pulsar 150 or Discover 150f. Theses bikes are grabbing the market from very long.
These mentioned Bikes from Different Riding Style you can choose.