Kellett is one of the schools of choice amongst my friends and colleagues. Chinese International School and Canadian International School being the other two, but they are less useful if you only plan to stay a couple of years and need to reintegrate your children into a UK system, if that is where you are moving from. Obviously there are other international schools which align to the respective school system of various countries which are generally pretty good (Australia, German-Swiss etc) if you are from elsewhere. The ESF schools are generally well regarded and very popular too. I don't know a single Western expat who sends their children to the new wave of schools, only locals and Mainland Chinese, though I'm sure some must do.
If you have read some of the other posts on schooling and relocation on this forum you will know that nearly all international schools, including ESF are very heavily over-subscribed and you can't guarantee you will get into your school of choice. If you can get a corporate debenture it will really help. Hopefully you will also be aware that the ESF schools (though not the kinders) mostly have catchment areas and you can only usually apply for the one in the zone you are/expect to be living in.