I highly recommend everyone to sim their characters to find out their exact stat values.
Intellect: Raw damage increase on everything.
Haste: Increases cast and tick speed.
Mastery: Increases the damage done by your demons.
Versatility: A weak damage multiplier and damage reduction.
The best way to calculate stat priorities for your character is to "sim" your characterFind out how to sim
Troll > Orc > Goblin > Blood Elf > Undead > Nightborne
Human > Gnome > Dwarf > Worgen > Dark Iron Dwarf > Void Elf
The enchants you use depend on your stat weights. Both Mastery and Haste enchants can be useful, but you should sim yourself before enchanting your gear.
Mastery: Accord of Mastery
Haste: Accord of Haste
Mastery: Masterful Navigation
Haste: Quick Navigation
Gems are dependent on your stat weights. Both Mastery and Haste gems can be useful. It is always best to sim yourself before socketing your gear. It is also recommended using one Intellect gem if your Intellect is simming better than both your Haste and Mastery.
Mastery: Masterful Sea Currant
Haste: Quick Sand Spinel
Intellect: Leviathan's Eye of Intellect
Health Potions: Abyssal Healing Potion