NUS chem engin is ranked 6th in the world according to QS rankings. Its very up there. I've heard a lot of Chen engin grads working in the petrochem field. Hence they make a lot of money and competition for the course is very tough. Not to mention research in chemical engineering is booming at this moment. A lot of focus is on materials that chemical engineers can develop. You will literally be on the forefront in tech research.

Chen engin is much more stable in a sense than business. Engineers will never lose demand. You learn a hard science while business is soft skills. A minor in business would actually suffice. With a minor in business, it will complement your Chen engin major. Not to mention business grads are too saturated at this point in time.