I answer this question a lot on Pprune. My answer is always that you don't want to go there as an F.O.. People ignore me and go anyway. One year, or less, later they are moaning and complaining about their job.
I've worked in Taiwan. I know many Taiwanese pilots. I know what I'm talking about. Don't go to China Airlines as an F.O. You will be miserable.
I like Taipei and I like the Taiwanese people. China Airlines has some pretty serious internal issues at the moment though so it is best to stay away, even as a Captain.
It used to be that China was better than EVA. Now things have detiorated so much at China that EVA is looking like the better option. At least with them you have a chance to upgrade after 7 to 8 years. At China that is unlikely for an expat. They'll lie to you and tell you what you want to hear to get you to commit, but they won't honor their promise.
If you want first hand info on how they treat pilots send a PM to etops777, he will tell you the inside scoop. He's Taiwanese and he left. That says a lot right there.
Always remember that in Taiwan ( most of Asia really ), the day you sign your contract is the best that contract will ever be. It only gets worse. Little things get taken away bit by bit until you've lost 20 to 30 percent of your original package after just a few years.
You've been warned,
Typhoonpilot