Like the previous poster said, heal over time spells made at the spellmaking altar are more magicka-efficient than the built-in instant spells. If you have access to the spellmaking altar, it would be a better idea to make your own restore health spells.
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I am very high level with VERY high magicka and I use 'heal superior wounds', the second most-powerful / costly one in the game (heal legendary wounds is kind of overkill for a general heal spell) but custom spells are the best way to go for 'odd one out' spells.
For example in terms of restoration I have a 'Phoenix from the Flames' spell which costs a ton of magicka but refills ALL my health in a matter of seconds.
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