HCMC was formerly Saigon. Plus side for Vietnam, including Da Nang, is that I found the majority of locals friendly and helpful. Singapore is great but I didn’t feel a sense of community. My time in Vietnam I made loads more friends than I did in Singapore. It’s an individual thing, if you are into hanging out with expats and have business then Singapore is for you. But if you are a tourist looking to explore and see things that are still relatively cheap Vietnam is the place.