it's hard to narrow down your choice of weapon to just one. With the exception of staves and polearms for the more mysterious survival spec, guns and bows are the defining tools of the hunter. Styles vary from extremely minimal and non-flashy to gem-encrusted, skull-mounted, and on-fire...
For either helm, use a Relentless Earthstorm Diamond for your meta gem (this is the best possible option for hunters, period) and a red agility gem for the yellow socket, ignoring the bonus. If you REALLY want the bonus, use an agility-crit orange gem. The helm enchant (Arcanum of ...