If you're really asking which brush will give you the best results with soap, that would be the one with the strongest backbone - my Rudy Vey "Chubby 3" which has a very dense TGN 3-band 31.5 mm knot. Were you asking only about Simpsons? If so, my vote goes to the Chubby 3 in Best, which is very similar to Rudy's brush - and only twice the price...lol.