I’ve lived in both the mainland and in Taiwan, as well as numerous other Asian and European countries for work. As for the mainland, I’ve been up in Northern China, Beijing and Shanghai, as well as travelling to various second and third tier-cities for various work-related reasons. Taiwan - I’ve only ever lived in Taipei. My opinions are as follows:
Concerning work-culture, both places are pretty gruelling, Taiwan more so, but nothing compared to Hong Kong. Wages are terrible in Taiwan, and they reduce with inflation for the majority. The mainland has real promotion opportunities, and is far more of a meritocracy than Taiwan, which is more first-come first-serve.
Ability-wise, I’d say mainlanders are more capable workers than their Taiwanese counterparts, especially those just leaving university. However, Taiwanese are excellent with simple tasks that do not require independent thought, as if given instructions, they will follow them to the letter. Both work equally hard, and can 吃苦. Access to English-speakers is probably easier in a mainland tier-1 city, but lower down less so.
Cost of living can be high in the mainland, but equally so for Taiwan. I’d say pound-for-pound, Taipei housing is more expensive rental-wise than mainland tier-1 cities - for a similar capital outlay, you get far more space in Shanghai or Beijing, however, access to small flats at the bottom of the market is probably better in Taipei, as there are far less workers on low wages to snap-up rental properties, and less methods to access the properties (apps etc).
Public transport: Taipei is excellent and clean, Shanghai and Beijing are clean enough, but the cities are so bloody big, it takes an age to get anywhere. Again, due to the size of the cities, you can get a lot done in one day in Taipei. Beijing or Shanghai, plan on one meeting a day if it’s across the city.
International flights from Shanghai or Beijing are a nightmare, Taoyuan and Songshan are excellent - on time, reliable. The only thing you can rely on in mainland tier-1s is a delay.
Healthcare is far better in Taiwan, mainland medical care is terrifying, and access to it is not good. Doctors are overworked in both places.
Food, I would say food safety is pretty similar, however, I would argue access to better quality ingredients is available in the mainland, as you can get what you pay for. Tier-one cities are truly international, so you get proper foreign food and ingredients. Taiwan is not international, and so choice suffers.
Air quality is improving in the mainland, and not in Taipei. I have a number of Taiwanese colleagues and friends who are based in Beijing, who get various nasal and skin allergies when they come back to Taipei for business trips, that then disappear again on return to the mainland.
Manners: improving in the mainland, regressing in Taiwan.
Can’t comment on education, but both systems seem equally hard on the children, again, nothing on Hong Kong though (e.g. kindergaarten entrance exams at 16 months).
Freedoms are, on a day-to-day basis almost exactly the same. The only thing that affected me was lack of access to the internet, and having to find ways around it. Otherwise, I’d argue the mainland is a pretty free place for most activities, unless you’re into certain activities.
Day-to-day convenience, mainland is leaps and bounds ahead: everything is available to order on your phone, paid for on your phone and 24-hours. Everything is seamless. Taipei is… not. Again, a common gripe of my mainland-based Taiwanese friends is the lack of convenience when they return home. The only thin I have found more convenient in Taipei is access to convenience stores.
Activities-wise, Taiwan is small, so its activities are more easy to get to, but less varied due to the lack of variation in climate. The mainland is so large that you can do whatever leisure activity you want, if you are willing to travel for it.
Overall, I’d rather live in Taipei than Shanghai or Beijing on the sole basis that I was sent to a boarding school in the country, thus am uncomfortable when couped in a city for too long. It is so easy to leave Taipei for the mountains or beach, and impossible to escape Shanghai or Beijing. Taiwan is essentially a sleepy village, it’s sedate and not much goes on, which may or may not be a positive, depending on your view. I think Taipei balances everything well, but that’s because I’m not a local struggling on a local-wage. If I were, I think I’d be queuing up for a job across the water too