Hi,
As someone who's living in Singapore, I believe INSEAD is the best, followed by NUS, NTU and SMU respectively.
However, choosing what's good for you depends on multiple factors. For example,
- Choosing INSEAD might not be good for someone who is looking for career switch. The program is only 1 year, and catered mostly to those who are already high-flying in their pre-MBA. You might make it in but the exit will be challenging.
- Choosing NUS, NTU and SMU might be good if you plan to work in the region. But overseas (US,EU,..) their reputation might not be that well-received. Plus, the connections you make at these 3 schools might not be as extensive/prestigious as INSEAD (personal opinion).
- Financial support seems to be more generous from NUS and SMU in my experience.
Most importantly, and this is something that is often overlooked by alot of applicants here, is that gaining an Employment Pass in SG is getting increasingly difficult. MBB is slowly refusing to sponsor working pass (something similar to H1B in US) to foreigners due to government's tightening restriction. I am not saying it's impossible but it might be a deal-breaker to firms when considering you vs someone else who has a citizenship/Permanent Residency.
Hope this helps:)