For some reason I should put death 3rd because it is a stealer class.Life second because life is a support school.But for first it should be storm because health for some reason doesn't really matter.Plus you could blade and tempest to 1 shot enemies.Also when storms are high level you don't have to wry about accuracy.
Do you even know what secondary schools are? If you train Storm as your secondary school, your health doesn't automatically go down, and it is not possible to train Tempest as it is a Storm exclusive spell. Also, even if you use Treasure Cards, Tempest wouldn't deal very high damage since it is an Off-School attack, and there are very few gear at higher levels for non-Storm wizards that boosts Storm accuracy.
