I have a Charles Owen ventilated jockey skull. That's nice and light. Makes my forehead sweat a little where the padding is but it's nothing compared to what my old hat was like! The harness also has a really nice soft squishy leather. Very comfortable
Also have a Ventair fixed peak. Only really use this for competing, however, to compare both of mine, think I prefer the Charles Owen for ventability!
Just a warning - depending on your head shape you may be limited to what you can get make-wise. The Ventair fixed peak fits me well (albeit with some extra forehead padding in), however, when I wanted a skull cap the Ventair one totally didn't fit me.
Also depending on what safety standard you want highest in order snell pas or astm lowest is bs with a kite mark.
Unfortunately all the really vented ones I found (except troxell) only have lowest standard. My head gets soaked, literally like I e been in the shower. So I chose thhttp://www.equestrianclearance.com/westgate_efi/gatehouse-conquest-suede-riding-hat/index.htmle gatehouse
Which is only the lower standard and the first time I've done so
My theory was that all their other hats are a much higher standard and hoping that apart from the vents the rest if this one would be too -
I just needed an everyday one I could wash the linning!! However I only school in it. Use protector for jumping and hacking
i used to have a charles and owen one and i used to sweat in it a lot but then i outgrew it and got a champion ventair hat which i believe its purpose is to ventilate your head to not sweat as much (i don't really know a lot about these hats but i'm just telling you from my expierience) and i never sweat in my champion ventair and also i find it very comfortable to wear