With what I have equipped there I have 2290 SP, 19% crit, 244 Haste. (assuming I'm self buffed)
I have other gear that would make my stats look like: 2180 SP, 15% crit, 489 Haste. (again assuming I'm self buffed)
Guess what im saying is which one do I need more Crit or Haste. Crit is nice for DoTs, but haste is nice for my other casts, yet I don't notice the haste to begin with. In a 10m I do pretty shitty, only 3.5k, in a 25m I do 4k+ easy.
Mate look above hit cap anything with hit is a downgrade..
now besides that...any gems (besides the 2 blue gems u need for ur meta that should be 12sp +10 spirit) should be spell power gems...
now ... crit > haste when u have the required haste to get 2 mind flay's in between 2 mind blasts with raid buffs.... though too much haste can lead to dps loss cause if u have 1 free sec u either lose 1sec witing for ur mind blast or cast something else and lose from 0.5 sec to 1.5 sec...
hope i helped