From my experience I've found 2 foams really work for me
Magifoam
Bilt hamber snow foam
Both have been great but magifoam does get the upper hand, on my Eddie that's coated with best of show I can get a touches wash from magifoam
HOWEVER
It all depends on how looked after the car is...IE is it protected? How long has it been since it was last washed
All these points can make a big difference to how good a potential foam is,and let's not forget!...snowfoam is only an aid of cleaning to help reduce damage to your paint! But as I said magifoam does win for me and I have had touch less wash from it depending on how it's mixed
Hope this helps, your always welcome to drop me a email for some advice or even come down and we can demo some of my foams I have