Haste

I suggest checking out maxdps.com and looking at the suggested gems for the elemental shaman.

I believe +spell is king, followed by (+spell/+haste) followed by +haste.

the difference doesn't seem like that much but over 5 shaman and over multiple gems it starts to add up.

I have 1002 spellhaste with procs, and it blows.

The thing about spelldamage stats is that every point in Spelldamage makes Crit and Haste better, Every point in Haste, makes Crit and Spelldamage better, and every point in haste makes both Spelldamage and Haste better.

If someone has the time and effort they might make a three point chart of it showing equality curves for all the three stats. (don't really know the proper terms, but whoever knows what I'm talking about should know what I mean)

However, the DPS increase from haste is linear after patch 2.2 I think. Haste increases casting speed, it doesn't give a cast time reduction. 10% casting speed increase you can cast 1 extra spell in the same time you could previously cast 10 making that 11 1.5second cast time spells in 15 seconds. If it was a cast time reduction you you could cast 11.1 and this would make the increase exponential. Now it is linear.