At 90,000, you would be living the really really good life, especially if it's out of Taipei. I know very few people (local or Taiwanese) doing any kind of job who make that much!
However, the hours sound exhausting. I'm no expert on teaching, but it seems that dealing with 30 elementary-schoolers for 1 hour per class would be much easier than dealing with 10 3-year-olds for 9 hours. With the former, your job is to teach. With the latter, your job is to teach and babysit.
For comparison, average monthly salaries last year according to a random blog (I'm too busy to check against gov't data right now, but this looks about right)...
Age 20-44: NT$35,659
Proportion of workers paid more than NT$70,000 a month: 5%
More than NT$50,000 a month: 17.4%
Wow, reviewing these numbers again, I really am happy I decided to leave Taiwan behind...
Here is how I was spending when in TW to give you an idea. I had an office job that paid well, but not as well as either of your offers. I'm very very frugal, so it doesn't need to be this cheap.
Rent: NT$7,000 for a room in someone else's apartment (Zhonghe, New Taipei)
Food: NT$9,000 only eating out, never had time to cook
Transport: NT$1,000 on the metro and buses; about 1/4 that if the weather permitted biking
Phone: NT$1,200 for unlimited 3G data
Total: NT$18,200 for my basic expenses
If you lived like I did, and were paid NT$90,000 a month, you would have NT$72,000 of disposable/savable income. That's US$2,300 each month. So the pay is quite good, yes.