I'm going to assume that you mean KCS - since I've never heard of KSC before and investigation reveals that it is a relatively unknown ICO. Please let me know if I have assumed incorrectly.
That depends on your tastes: I love them both, I really love those coins.
KCS is undoubtedly the safer of the two coins: that's not to say that the team and company behind CXO are bad - just that their coin is far more unknown. I believe KCS to be strongly undervalued and that it will climb significantly. I believe that CXO has even greater potential ROI - the market cap of KCS is about 100x greater. I suggest that you dig into both a bit, since there is much to learn about each token. The CXO whitepaper is fairly simple to read and explains the token economics rather well. KCS is going to be a bit tricker because the platform is constantly developing - but I've been with them since the early days and should be able to help you with any specific questions which you may have.
For what it's worth, I own a greater percentage of CXO than I do of any other coin. I work that out using this method: https://steemit.com/cryptocurrency/@bitbrain/how-much-to-invest-in-a-crypto
But I also tend to have a more risky appetite than most and I'm prepared to take chances, so as a major investment CXO probably suits me more, you may be different. At the end of the day, there is nothing stopping you from buying both. KCS starts to have benefits as soon as you have 6 tokens - an investment of less than $10. CXO has no real minimum limit. I believe strongly in diversification, so if you are sitting on the fence, perhaps that is the best option.