Generally with most tanks you want Item level over all stats as more stamina and main stat will always be good. However when you are look at the same item level then the priority to look for should be:
- Item level
- Mastery >= Haste
As to what you should be running when you’re looking at min maxing your dps then you should sim yourself as your weights will change based on your current gear.
Agility: This is your primary stat as a Guardian druid and does a bit of everything. It increases your damage, the armor bonus granted by Ironfur and it also increases your chance of dodging attacks.
Versatility: This just increases all your damage and healing done while reducing all damage taken.
Mastery: Mastery: Nature’s Guardian Increases your maximum health and also your healing received. Additionally we gain a small amount of attack power from mastery.
Haste: is very nice for guardian as it not only reduces our GCD’s which results in more rage generation and damage but our DoT’s also tick faster based on our haste this counts Thrash, Moonfire and the feral affinity bleeds of Rake and Rip, this results in a significant dps increase.
Critical Strike: This increases the chance for your spells to deal double damage.
Zandalari Troll: Shrine of Bwonsamdi is a really nice passive damage boost on ST and it is a small HPS boost.
Troll: Berserking is really nice when paired with your CD’s, it’s really strong on AoE during berzerk.
Worgen: unfortunately there aren’t really any good alliance races for damage, the crit you gain from Viciousness makes worgen the best for damage.
Night Elf: If you’re interested in M+ Shadowmeld is invaluable at creating new ways to skip mobs.
Kul’Tiran: Brush it Off provides a small HPS gain which defensively is the best you will find out of the alliance racials.
Rings: You will enchant your rings with Enchant Ring - Tenet of Versatility if you are looking to be defensive other than that you should sim yourself to see which would be the largest dps upgrade for you.
Weapon: Enchant Weapon - Sinful Revelation, Enchant Weapon - Celestial Guidance, Enchant Weapon - Lightless Force All 3 are viable options. Sinful is best for damage on single target, Lightless Force is best for damage on Cleave + AoE and Celestial Guidance is best for defence.
Similar to ring enchants you will gem for versatility if you are looking to be defensive and will sim yourself to find out which stats would be best for you offensively, otherwise.
Flasks: Spectral Flask of Power will be your go to choice for pretty much all content. Spectral Flask of Stamina can be used if you feel like you need a larger health pool to survive the content you are doing.
Weapon Oil: Shadowcore Oil
Armor Kit: Heavy Desolate Armor Kit.
Healing Potion: Spiritual Healing Potion.
Augment Runes: Veiled Augment Rune.