My daughter is now in K3 in Victoria, and I was amazed by her excellent command of English. Her Chinese is not as good as her English, but she has good accent of Mandarin.
If location and $$ is not your consideration, I think Victoria should be a better choice, because Victoria is more well known in both HK and PRC. In addition, Victoria has a good through-chain primary school and secondary school, called VSA, in the Southern District. VSA is quite similar to CKY, in terms of facilities, school systems, language environment, and school fees. But Victoria is already an IB school, while CKY is not. Graduates of Victoria Kindergarten has preference to get admitted, while outsiders are difficult. (Don't argue which one is better, as both of them are good and parents in HK don't have any other substitutes in the market. (e.g. similar to international schools while Chinese is emphasized.))
If you want to enjoy free education, you may still take the lucky draw even when you get admitted by VSA.
The school fees are excluding other fees such as "misc. fees" and overseas education/excursion trips from P5 and above.
If you choose VSA or similar schools running IB, you really need to ask yourself are you prepared to let your child to complete his/her pre-University education in the same setting? This is because you will not be able to join the SSPA system when your child is moving on to the secondary school. You are left with the DSS schools if you wish to "return" to the majority education system.
Personally, I am all for the IB education system especially if you are planning to let your child to study aboard later on, but it does depends on the school management and teachers to make sure its' successful implementation.
VSA do emphasis and encourages students being multilingual (Putonghau and English are the basic two languages taught and used at school) and having international views. This is achieved in their regular projects and presentations.