It's Subjective
"now last question, wich is better KO or kiss III?"
Like all systems, you will have do your "due diligence" and make the decision, not rely on just what others say.
Having said that...I use KO.
You also are leaving out a very well documented system in Red 7. It, too, is easy and quite remarkable.
In deciding which system to use, one of the factors for me was the amount of information available for each system. For instance...you take KO and KISS. You'll probably find a lot more information about KO than KISS simply because more people use it. Just do a search here on the two and see how many more hits you'll get with KO vs KISS. I'm not saying KO is better (though I believe it is), but more information on the system helps. That shouldn't be the only factor, for sure.
Factors such as how often you will be playing, how serious you are about the game, how much time you are willing to devote to learning a system, all play in the decision-making process. If you plan on doing this full-time and have the time available to learn, you may even want to learn a more difficult system...(level 2, 3, etc.)
Any reputable system will get you the money, you ultimatly have to determine what's right for YOU.
Regards:
PM