Good job. #5 doesn't have the K like #4 and #6, so I prefer the other 2. #4 and #6 are the same in my vision for the logo. The difference is if they're used with or whithout the text. If used without the text I prefer #6.
What do you think if it's usability in other colors and backgrounds? For example, if used in a black or blue background? It would be nice to see some sports or movement.