We want a significant amount of haste for dungeons to make sure that our playstyle doesn't feel clunky. I personally run 20% haste this season. Then versatility is our best all-around stat that works great in every situation. Crit is very strong for our aoe dmg but falls behind on pure ST as it doesn't affect Lava Burst. Avoid mastery as much as possible for keys.
Critical Strike: Critical Strikes give us mana back if talented into Resurgence and increases output when we land a crit.
Versatility: Increases our healing and damage by a flat amount and reduces the damage we take by half of that.
Mastery: Increases our healing done to targets based on their current hp, the lower their health, the more healing we do.
Haste: Most of our abilities don't scale with haste which makes it relatively weak, especially in a raiding scenario. It gets more important in dungeons.
Pandaren - Gives huge output increase thanks to the double effect of the food buff thanks to Epicurean
Dwarf - The best race for mythic+ content by far. Might of the Mountain is a strong passive DPS/HPS increase, which scales with the amount of critical strike we get throughout the expansion. On top of that, Stoneform is the biggest game-changer defensive racial that can completely negate some mechanics.
Tauren - Just like dwarf Brawn is a strong passive DPS/HPS increase, which scales with the amount of critical strike we get throughout the expansion.
On top of that, Endurance helps with one-shot mechanics thanks to extra stamina, while War Stomp brings additional cc potential.
Extra note :
Goblin used to be extremely important for shamans, thanks to Rocket Jump. It helped a lot with some mechanics/mobility.
Thanks to the new talent tree and return of Gust of Wind, a goblin is no longer required, and we can opt for a more throughput-oriented race.
Cloak - Writ of Leech
Bracers - Devotion of Leech
Weapon - Sophic Devotion
Legs - Temporal Spellthread
Ring - Devotion of Critical Strike
Feet - Watcher’s Loam