This is a good time to revisit one of my harshest critiques of private degrees in Singapore. You can read this old classic here
The article came out in 2015 and was so harsh, tuition agency blogs wanted to reproduce it (probably to scare parents). Over the years, I think there have been some positive changes that warrant a revisit of the contents of this classic. 
First, I think we should think about what has not changed. The gap between a private degree and a local degree continues to be wide – as high as 33% in some cases. In fact, the situation has become much worse.
The rule of thumb we should apply is that a diploma will get you a salary of around $2,000. Upgrading a private degree will add $400 every month, but this is a far cry from a local degree