The advice of FT's who've taught both in South Korea and in China should be heeded imo.As you are almost at the ceiling age for foreigners wishing to teach in the former country,maybe it'd be wise for you to forget about teaching there.China's ceiling age for FT's would appear to be 60 at present.And,being a much bigger country,it needs more FT's than South Korea ever will.My advice is that China would be a better choice for you,but having said that,it's your choice in the end.Whatever you decide to do,good luck!