Dont just look for a name, look for flow rate.
To get the best out of snowfoam (which ever company you use) you need at least 7L Per Minute, this will produce a nice "whipped cream" type of foam.
Also find out if your in a soft or hard water area, as this too can affect the way the foam will work and how much product you need compaired to water.
If money is no object then its got to be Kranzle, expect to pay £300 plus for one, Greg at Valetpro is a man to talk to about them.
Otherwise walk into B&Q and look at the Bosch etc, also look in Machine Mart, again look at the flow rate.
As for the foam lance, Tim at Clean Your Car.
When you have the PW and Lance then its time to find out which foam works best. Look for a PH neutral product, for instance ValetPro, Espuma and of course Bilt-Hamber.