here is my new answer to the Z vs K question
how much time do you want to spend on your car? If you're a frequent waxer Zaino might be the one for you. You can layer and layer Z on a white car and make it shine. Most people that use Klasse have long gaps of no Klasse application. Some use a natural carnauba topper to give more depth which they do every other month or so.
it seems that people always answer, this is better, this is better, but now I think it's not which is better, it's how would you like to use it (assuming you don't like one shine over the other)
The match between the two is pretty much neck and neck but different people tend to like each product a little more than the other. So the answer to your question ends up being, you'll have to try out. So at this point the new question is which program would you like to adopt? (as I don't think money is an issue here)