it really depends on the factor u r looking for.
for eg, ur frens r rite tht its not so hot but have they ever
considered the protection it provides? a helmet tht is fitted
nicely provides the max protection & comfort. they want
cooling? get on with proper air vents 
when u buy helmets, the right size is actually a little bit tight,
when u wear it, try to move the helmet right & left without
moving ur head, it shld have minimal allowance for movement.
hhhmmm, maybe u get wear those bandanas or even those covers so tht
ur cushions won't smell so fast?