I always measure the "live-ability" of a place based on the 4 necessities: air, water, food, and bathrooms.
Air: In Taiwan, you can actually see the blue sky on a clear day. In China, there is no such thing as a clear day or blue sky in any of the big cities.
Water: In Taiwan, you can drink potable water from the faucet. In China, you have to boil the water from the faucet before you can drink it.
Food: In Taiwan, I am brave enough to eat most everywhere, even from the street-side vendors. In China, I never eat from the street-side vendors or the cheaper restaurants because I would get diarrhea.
Bathrooms: In Taiwan, there are clean public bathrooms most everywhere. In China, I am always looking for the nearest McDonald's since they have the cleanest bathrooms.
Other things that make Taiwan higher quality of life than China are--
Mail service: In Taiwan, pretty reliable 99% of the time with the unreliable part mostly from customs. In China, maybe 70-80% reliable(???). The unreliable delivery services/logistics are what is keeping the online purchasing from taking off in China. Amazon China is even thinking about building their own delivery network because they can't trust the mail/delivery services.
Healthcare: In Taiwan, Western-trained doctors, modern facilities, less placebo drugs. In China, I was scared to get sick, even for diarrhea, and I couldn't even trust that the aspirins are real.
Customer service/retail purchasing: In Taiwan, less haggling of prices, some warranties on certain brands, etc. In China, haggling of prices is expected and seems to be always an extra 15-30 minutes overhead for just about any purchases, and almost no warranties.
Freedom of speech: In Taiwan, freedom of speech, but in business, you do need to worry about getting sued for liability. In China, what is freedom of speech?
Internet: In Taiwan, free public wifi at all the MRT stations and other public places, 50Mbps for about 30-35US/month, no government website censorship, etc. In China, well...you get the idea.
All these are my reflections based on my 1-month stay in China about 6-months ago. Yes, a month was all I could take in China.
But things may have changed in China, because I hear China is changing very fast (faster than Taiwan, which may be the only advantage China has over Taiwan).