I see that you have not had many replies to this thread. I haven't tried any of the Werkstatt products, so I can't give you any useful information there. However, I have tried the other 3 products you mentioned -
Klasse AIO and 1Z Express are fairly similar types of products. Both are mainly chemical cleaners with some protective qualities as well. They are extremely easy to apply and remove either by hand or machine. To my eyes, Express looks better when used as a one-step. However, I like AIO better as a paint cleaner and as a base for a sealant or wax.
Menzerna FP II is an excellent straight finishing polish (no protective features). It will remove minor imperfections in your paint and leave your finish with a very glossy look. Just follow up with your choice of sealant/wax. That being said, FP II seems to work best with a rotary machine. It can be used by hand or with a dual action machine, but the results may not be as impressive.
Just my thoughts. Your mileage may vary.
