Basically the logic is that the higher your spell damage, the greater the chance is that you will land a kill on the insta.
Spell crit does nothing for your instacrit nuke..

Personally, I think that until ~900 spell damage you should pursue spell damage mainly.. when you're 900+, you can consider spell crit.


When looking at it on paper, spell damage seems like a superior stat in pvp. However, there's a great factor that speaks for spell crit: surprise.
If you get 4 lucky crits with a round of lightning bolts, you may very well kill some classes, and they don't see it coming.

So the big pro of spell crit is its unpredictability. As your spell crit goes up, your damage output is more and more unpredictable, which can generate a good amount of kills when your insta is on cooldown.