In general, the Damage stat on your character sheet can be trusted. It takes everything into account.In general, the Damage stat on your character sheet can be trusted. It takes everything into account.
Because of the complicated interaction of these stats, and the way they multiply by weapon damage, it's difficult to say that one is 'better' than the other. It depends mostly on the amount of each you have. If the two come out to a wash, keep in mind that increasing attack speed has the ancillary benefit of improving your mobility in between casts, while increasing your stats has some survivability benefits.