Something I noticed as I have been gearing up my team at L80 is that my Elemental Shaman's SP was always way higher than my mage, spriest and boomkin.

It was way easier to gear up my shaman. One example is the titansteel guardian mace. My mage loses out big on a good weapon until I get Kirin Tor to exalted (I think?). I suppose I could have planned around this but I never bothered. My mage is still about 300 SP behind my shaman and boomkin and I have been focussing on gearing him up.

Anyway, If you plan on purchasing a bunch of epic gear from the AH to quick start heroics, the elemental shaman is the best choice for DPS IMO - Revenant's, Windripper, Ebonweave/Spellweave, Titansteel etc. Access to mail, leather, cloth and shields is a huge bonus for a DPS class.