I have a big head, and Troxels tend to fit me best - I don't care as much for the "old style" Troxels, with the more plastic/shiny exterior. . .they really felt like I had a bowl on my head. But now I have a Troxel Sierra and really like it. Lightweight, cool, looks good (I got the tan one - has a suede/leathery look on the exterior).
The most important thing is to just go to a tack store, with staff who understand helmet-fitting, and let them help your husband find what will work best for him.
"Parelli horsemanship is just like painting by the numbers. You need absolutely no skill. You just put this color here and this color there, and when you're done, you have ... a mess no one wants." mp