Both are very good polymer sealants that last a long time. I feel the real difference you will find is the prep and "proper" application ways.
The advantage of Klasse is that there <strong class='bbc'>isn't[/b] this "exact-way" to apply it. You can experiment around with different cure times, layer thickness, damp towel or not, or wax topper or not.
The Zaino advantage is just the opposite. The instructions say you have to apply it exactly "this-way" which makes it seem like a lot of work. The truth is, it isn't that hard or a lot of work (just Z-7, Z-1, Z-2, Z-6.) These long instructions is just for what Sal Zaino find's to be the "best way." So no need to experiment here.
As far as application, Klasse may need less products or time, but may need just as much as Zaino. For example with Klasse you can wait 24 hours for it to cure if you want to, or you can apply layers immediately after. You can just use Klasse AIO or SG, or use the Quick Detailer, Clay bar, car wash, Wax topper, etc. It all depends.
For shine, Zaino is a reflective, cold "wet" shine, whereas Klasse is more natural and "deeper" IMHO. Also, with Klasse you can add a wax topper for a warmer and an even deeper shine.
For pricing, Klasse is cheaper per ounce, and what do I prefer?
Klasse for darker colors because I prefer a more subtle look, and Zaino for lighter colors, especially metallic because I like how Zaino "brightens" and makes the paint.... just happier

Oh, and I also prefer Klasse for cars I don't spend much time on and other people's car.
No matter which one you choose, they are both good choices. Good luck!