Agility > Mastery > Critical Strike > Versatility > Haste
Agility: Increases the magnitude of your attacks and abilities. This is your most important stat, which is why you want to look at the item level of each item rather than the stats on it. A higher item level is usually better because it gives more agility.
Mastery: Your mastery is called Mastery: Sniper Training, increasing the range of all your ranged abilities and the damage of all abilities. It affects most of our damage and is usually our best secondary stat.
Haste: Increases your auto attack speed, increases focus regeneration, reduces the cast time, and the cooldown of Aimed Shot. Not bad, but we have better stats choices for MM. In AoE situations, make sure to have enough haste to be able to cast 2 Aimed Shots and 1 Rapid Fire during your Volley window.
Versatility: Increasing all your damage and healing done and also decreases all damage taken. This can provide a bit of survivability that is sometimes needed for hunters.
The best way to calculate stat priorities for your character is to "sim" your characterFind out how to sim
Human is also a decent choice for Alliance players thanks to its The Human Spirit passive, which provides 2% more of all secondary stats.
Chest: Enchant Chest - Waking Stats
Legs: Fierce Armor Kit
Ring: Enchant Ring - Devotion of Mastery, Critical Strike, Versatility or Haste (depending on your stats - SIM yourself!)
Weapon: Gyroscopic Kaleidoscope
Every gem with 2 different stats works (these provide more stats than the single-stat ones). It is situational and will depend on what stats your character has at the moment; the best way is to SIM your character on Raidbots to see which stat you need the most. Make sure to have 1 Diamond equipped (this one is more powerful).
Rune: Draconic Augment Rune
Healing potion: Refreshing Healing Potion