Int > Haste > Crit > Versatility > Mastery
Crit has synergy with one of the new talents, Divine Aegis, which increases this stats value a lot when talented.
Haste impacts how fast you can cast your spells which is incredibly important for raid ramps in particular, as more haste gives you the ability to fit in more atonements into a single ramp before they start falling off.
For dungeons more haste can be the difference between the life or death of your party members, as burst damage in the new dungeons can happen incredibly fast. This makes it critical to have a lot of haste so you can fire off your damaging spells to heal through Atonement.
Due to Mastery being the only stat not granting any extra damage it loses some value in Mythic+ and difficult raid encounters where you would like to squeeze out as much damage as possible to help out the group in downtime.
Goblin grants access to the ability Rocket Jump which can be incredibly powerful in the right situation, as priests in particular are lacking in terms of burst movement cooldowns. Goblin also gives a flat 1% haste increase from its racial passive, Time is Money, which is a nice bonus since haste is the best secondary stat for discipline. For most scenarios Goblin will be your go-to race as it gives you the best benefits out of all of them.
Trolls have Berserk which can be an incredibly useful tool in both raid and dungeons for Discipline Priests. In raid it can be used to speed up a ramp allowing you to complete it faster and being able to fit in more atonements before they start falling off. In dungeons it can be a nice boost during heavy damage when you really need to fire off your spells faster.
Blood Elf gives you Arcane Torrent, an AoE purge that also restores 3% of your mana. At best this will help you out whenever you need to mass purge and don’t have access to mass dispel, and at worst it is a nice boost of mana every 2 minutes.
On the alliance side we have Night Elves that come with the racial ability Shadowmeld. For those that are more interested in playing Discipline Priest in dungeons this racial is an incredibly potent and versatile racial. For example it can allow you to meld out of combat at the end of a wipe to resurrect teammates, perform skips through a dungeon or drop aggro at a moments notice.
Void Elf has the racial ability Spatial Rift. This racial can be situationally useful when used at the right moment as it creates and sends out a portal in one direction that can be teleported to within a short timeframe. This can be used to avoid certain mechanics and can be a lifesaver in the right hands.
Weapon - Enchant Weapon - Sophic Devotion
Rings - Enchant Ring - Devotion of Haste
Bracer - Enchant Bracer - Devotion of Leech
Legs - Temporal Spellthread
For the rest - Crafty Ysemerald
Healing Potion: Refreshing Healing Potion
Weapon Enhancement: Howling Rune
Augment Rune: Draconic Augment Rune
Phial: Phial of Tepid Versatility
Mana Potions: Potion of Chilled Clarity
Important note for Potion of Chilled Clarity: While using this potion, you’ll want to make sure you have a macro available to cancel this potion right before casting your Power Word: Radiance for your ramps. If you want to learn more, check out the Mana Management section in Rotation & Playstyle page of this guide.
Throughput Potion: Elemental Potion of Ultimate Power (Only use if you have no mana issues)
Phial: Phial of Glacial Fury
Throughput Potion: Elemental Potion of Ultimate Power
Invisibility Potion: Potion of the Hushed Zephyr