I use a visor insert - basically a sticker that goes inside your visor and creates an air gap between the visor and the sticker so that it can't fog up.
Works great! I don't even notice it's there.
I have the
Fog City brand
Fog City vs. ProGrip Helmet Visor Inserts - webBikeWorld
but for HJC and Shoei, the new visors have the
pinlock antifog option