I'm not saying KCS is shitty or anything, quite the opposite I've actually regretted not investing in it before and the platform is awesome.
I like the COSS project even more though, I like the Crypto One Stop Solution it represents, being a well rounded platform (ICO + FIAT) while always giving 50% of trading fees.
I don't think they are that much competitors, there is space for both, COSS being a bit "riskier" but also now being the one of the two where there is the most to gain from.