I can tell you not to buy the Rain X anti-fog stuff. Doesn't seem to work for me.
Generally when I stop at a light or going slow, I'll open the visor to keep it from fogging up. When I'm moving it's not a problem, enough air gets in to keep it clear.
The visor I can deal with, my bigger problem is my glasses fogging up. Even my "climate control" Wiley X glasses fog up - the problem is I wear a face mask on cold days and my breath will escape out the top of the mask right into the glasses. It's been so bad I have to lower my glasses a bit at lights or when going slow. Luckily, my eye sight isn't too bad, so I'm not "blind" when I take them off.
