AG formulate it so it does not foam, they say it does not need to which is true, the foam is not what makes it slick or highly lubricating.
All have pros and cons - If I had to pick one:
For me still the Sonax, leaves a great finish, kind on wax but cleans well and cheap through my local Vauxhall dealer.
CG has the edge on finish as it is a wash and wax product, but is mail order only.
The Zymol is the easyist to get, Halfords etc, and maybe the highest foamer.
Cant go wrong with any.