fit. then look for a quality helmet with a removable/WASHABLE liner. then a light weight one. one that breaths/vents. earplugs optional.
Shoei X-11, Arai rx-7 corsair, both over $400, but close if you shop around for a sale on SOLID COLORS.
Scorpion exo 700, but heavy, under $400.
HJC carbon.
good luck