Good question, it's a issue I've been thinking about for a moment.
I think the school and environment are more important for your kids than the country where you'll raise them. Bullying is actually a pretty severe problem in China and Japan. I've read many articles about that. It's not really much better than in any western country.
I myself actually passed my primary school years in China and it was definitely not a good memory. I got excluded from my classmates because I was the only one living with my grandparents while the other kids lived with their parents. My dad and mom were financially not so well off at that time so that they couldn't afford a flat for 3 people. Even my teachers didn't defend me because they thought I was supposed to live with my parents. They even thought my parents were having another kid secretly.
Ironically, I felt much better during my school years in Germany. Of course now I've realized it's not because Germany is better than China, it's because I was lucky enough to attend a decent school with decent teachers and classmates. My experience is also very personal and can't apply to every Asian kid. However, due to what I've seen during my years in primary school, and the fact that I'm pretty aware of the problems in China thanks to my solid Chinese skills, I'm less likely to say Asia/China would be a panacea than some western Asians who have never lived in their homeland.
Besides, it's also crucial to know what you want your kids to become in the future. If your kids are Asian or look Asian, and you want them to become somebody (especially big players in politics, finance, law etc.) , then it would be better to let them spend their formative years in an Asian country. It's easier for them to develop more confidence and ambition and have rich connections among people who look like them.
As for me, I don't really know. I don't have enough clout and resources in China to support my future kids if they want to achieve something big. After all, I'm just an ordinary person, like most of my Asian brothers. Sending my kids back means much more pressure, competition in school and workplace and a relatively lower living standard for them. Would they hate me for doing that ?lol
If I raise them in Germany, they'll never be popular nationwide (it's only possible in small circles), and they'll be exposed to racism outside Asian enclaves. The pros: They can be multilingual because of the polyglot friendly environment, more aware of the truth about racism and life is certainly less stressful in a developed country.
Anyway, there's no win-win solution. All you have to know is what you want to do and what you want your kids to do. As for me, I gotta fix the issue of "moving back vs staying" in the first place lol.