Originally Posted by
Ragekitty
The basic rule of thumb is if you have 4pc T12, you get hit/exp capped (or as close to it as possible) > haste > crit > mastery. (The last few are debatable depending on the fight.)
For gems, you aim for +40 Agi in red slots, +20 Agi/+20 Haste in yellow (if the socket bonus is +20 Agi), and +20 Agi/+20 Hit in blue (if the socket bonus is +20 Agi). Enchants are pretty obvious: +Agi to cloak + boots, +Mastery to gloves, +20 Stats to chest, etc.
The sticky is very helpful for these questions, BTW.