I'd first like to address the haste soft-cap. This describes the necessary haste to be able to fill every GCD. As of 5.4, you basically want to get as much haste as you can (assuming you are not using Assurance of Consequence), and then after around 11K haste you want to begin collecting tons of crit. Many monks state that they are pretty happy at around 13K haste, but some do go for more.
After reaching the haste soft-cap, there's 3 recommended ways to gem and reforge:
hit/exp caps > haste softcap > agility > crit > haste beyond softcap >>>>> mastery
Red sockets: pure agility
Yellow sockets: agility + crit
Blue sockets: agility + hit