NUS is a great university. Only a fortunate few get admitted there.

But it would be very difficult for you to go west for higher studies immediately, - in this age, 3 years could be one era.

If you would like to settle down in Singapore, which isn't a bad idea too, and would like to do higher studies there itself, then you can defer the bond till you finish your studies - provided you study there itself.

At NIT, you finish straight 4 years, and free to do what you want with your life - 6 guys, I heard from electronics in NITT went to IIMs last year. Many got two placements.  NIIT is not at all a bad option.

Anyways, it's finally  your decision.