Seems like very different courses he applied for, civil engineering as first, computer science as 2nd, and mechanical at other uni.

As a practising civil engineer, I can tell you university ranking really isn't something people care about. I can't say about other courses, but I was told university rankings play very little relevance anymore.

If he goes for precision or aerospace, your son likely will have to stay in China. This isn't a field that's hot in both Malaysia and Singapore.

As for civil engineering, it's very localised. Every country has different practices and different codes. If he studies in China, he'll likely stay in China. If he comes back to Malaysia or goes to Singapore, he'll have to adapt. Not a big deal, he won't be the first, but he must expect this phase.

In the end, nobody really put very heavy emphasis on university ranking. Singapore is full of Malaysian graduates from Malaysian universities that are ranked much lower than NUS and NTU, and it hasn't been a real issue so far. In fact, Singaporeans are complaining that local graduates are being discriminated against, with employers largely preferring to hire foreigners who would not need to pay CPF and would normally accept a lower salary than what the locals deem acceptable. That being said, graduating from higher-ranked universities have not been shown to be advantageous in terms of employability.

For example: in the recent tightening of Singapore's employment pass rules, Singapore's Manpower Minister said 'Instead, it is part of MOM’s regular updates to ensure that our qualifying salary keeps pace with local wage growth, so that foreigners are not coming in just because they are cheaper than local PMETs.'

If I were you, if all options are already very good, I wouldn't fret which is better in terms of ranking. If they're all good, I'll look at other factors - environment, cost, geography, weather, cost of living etc.