I have a 670/4.5 in GMAT
work: IT 4years
Indian
Acads: Average First Grade throughout
Extra-Curriculars: Working with 3-4 NGOs

I wish to apply to NUS, Nanyang, RSM(Rotterdam School of Management),AIM(Asian Institute of Management Manila)
Which of these colleges should I apply?

I have a admit at HULT.

I'd say these schools are well within your profile range. I'd say that NUS and RSM are more along the lines of safety schools, and I'd pick 1 stretch school - where you'd really like to go: IESE or Manchester Business School if you're looking at Europe, or HKUST if Asia is where you'd like to be.

You probably realize this but you're in a pretty competitive field (Indian IT exec) - so the more you can do to separate yourself from the pack (like focusing on your NGO experience in your application letters), the better.