If you don't want too big brush - Simpsons Berkeley
If you want bigger and denser - Simpsons Commodore
If you want a soft lather beast - Vulfix 2234
If you feel adventurous - get a handle and a Finest 2-band knot from The Golden Nib and glue them together.
Now sit and relax - boar, synthetic, and horse brushes suggestions are coming... Good luck with finding the right one for you.
-= Boris =- The man thinks, the horse thinks, the badger thinks, the boar thinks. The fish doesn't think, the fish is mute, expressionless. The fish doesn't think because the fish knows everything.