My go to helmet for trips with possible bad weather is the Shark Evoline modular. Most of the time I run in 3/4 mode, but a quick flip puts the chin bar down for a protected ride.

If it does not fit your head, you can push in on the foam lining until it feels comfy. Pushing in on the back of the helmet relieves pressure on the front. Easy to customize it for fit.

It has a built in breath shield, an air vent, and you can additionally crack the visor just a tad to keep everything clear if fog is an issue. Great helmet.

 

The best protection and least fogging for me has been Arai full face, then Shoei full face, then Harley (rebranded HJC) modular and finally a HJC 3/4 face with a face shield that fits close to the helmet.

 

I've used a 3/4 for a few years, no problem here when I am in the rain.

 

If you wear a fullface and in the rain a lot, make sure it has the pinlock system, which is basically two layers of plastic with air in between. Really does keep the fogging down.

 

On my last road trip I tried my new Bell Custom 500. We rode in quite a bit of rain and I did not have a face shield or visor. I had to hold my left hand over the top of my glasses so I could see. So my lesson learned is I will not take another long trip without at least a shield. I actually have a 3/4 Harley with a flip shield but I find it to be heavier and bulkier than the Bell. I have only owned one full face which was an HJC and I didn't like it. I'm still looking for the perfect helmet.