When wielding a tier 90 weapon, all surge spells will deal the same damage. The only possible benefit to switching to a different element of a surge spell at this level is exploiting an enemy's weakness to a particular element (such as the weakness of TzHaar to water spells). Since player warriors are not weak to specific elements, but rather all magic in general, it may be unwise to use any surge spell other than Air Surge in PvP due to rune costs.