Is October a good time to visit Taiwan, usually?

Yes, October is an ideal time for a visit. It would be cloudy, and rain sometimes in that month. The possibility of typhoon would be quite small. The temperature will range from 70F to 80F. Light rainy days won't influence the sightseeing a lot.
In addition, you are advised to take light jacket, shirts, pants, and an umbrella. May you have a wonderful time! :)

Thanks for your answer :)