skate helmets i think are the best, cheap, made to hit concret.....look kinda cool, the lining will stuff up over a season but i think if u r so concerned about your head u would replace a helmet exposed to salt water and sun ever 12 months anyway. IMO the visors on gaf and alike are crap. Just get some sunnies, most brands have surf sunnies with straps, mind u a good wipe out takes care of them, but id rather that than a visor breaking and cutting up my face.

Gath make helmets specifically for watersports, I've got one and it does the job just fine
gathsports.com/

you may also want to check out the helmet made by pryme.

I bought a pro tec.
Good helmet, looks good but I came in after my first few hours using it and the strap had cut into me.
Not sure if this is because I have beautiful soft skin but when I turn my head the strap rubs on my chin.

Tried it with no strap and it just falls off when you stack

Any way my point is to consider a helmet that doesn't need a strap like a good surfing helmet